MAKING MONEY IN CLASSICAL ATHENS

Tahir 6.1 Materials required to make one silver drachma.

Ore selected after sorting by hand

Ground ore feed to washery

Concentrate feed to smelting furnace

Work-lead feed to cupellanon furnace

Silver produced

Wr~ht prr drachma (kg}

16

IS

2

0.004

&tio matrrial:si/V(r

3711:1

3425:1

1140:1

500:1

With further reduction of the litharge by-product, c. 2 kg pure lead could be produced from the same materia!:

Litharge feed for resmelting

lead produced

Source: Author's own cakulauom bur cf_ n_40

Ochres

2

2

.'iOO:l

400:1

Vitruvius (Dr architectura 7,7.!) records that Athenian silver miners exploited ochre deposits if they found them. Ochre was the pigment in the glaze on Attic pottery; it turns both red and black, depending on kiln conditions and thickness of application (Noble 1966)_ Ochre is iron hydroxide, also known as limonite.'! Vitruvius state_, that the beq yellow ochre was Attic, but that it was no longer available; a generatJUn later, however, Pliny write' a~ if it was, while noting that Lydian wa~ not (liN 33, 158-60). Supply pre~umably varied, as with all mining products

Theophrastus (On Stone.1·, 53-4) report~ the discovery, by one Cydias, that yellow ochre turned to red when a fire burnt a store in which it was kept: red ochre (albeit of inferior qu:dity) wa~ then manufactured from yellow by roasting." This might have been new to the Athenians, but Old Stone Age man knew it well,"" as luve manv ,ince. There was 'more or less local produc­tion o(eJrthy pigment~ in almmt evny country' in 1945 (Taggart 1945, 66). but tht.: 1ndustry was then 1:1 term nul decline thanks to synthetiC produc­tion, wh1ch could provide btt~c: llJlour accuracy and quality. Atte extrac­tion, ochre is finely ground. wh!ch p, more or less easy dependmg. on the form: soft earthy type~. wh1ch un be shJ.ped into pastels or crayon.1, are easier than specular types. wh1(!1 T11J\' approach the hardness ot <;J.nd and require pestle and mortar''

There will be sand pa~:1cln i:; the lll.Jtcrial, which arc ~rparated by levJg.Jtion Mixed \Vith wJtc: :t :-or:m .Jn emulsion in which O(;lrl" ~cm.1ins

suspended while sand sinb P:c' <,!mplest w.1y to isolate ochre!' w mix the

129

T_ E. RIHLL

emulsion in a bucket and pour it out, trying to extract most of the ochre and leave most of the sand at the bottom. This, however, is primitive.

Ochre had to be levigated somehow, so we should look for archaeological evidence of the process; not everything in Laurium need be related to silver production.

However the ochre was levigated, surplus water was removed or left to evaporate, and the ochre dried to a powder. Mixing of pigments will be done at this stage, if indeed pigments were mixed- which should not be assumed."" Modern painters' ochre is the yellow to brown form of limonite mixed with clay. It should contain at least 20 per cent iron hydroxide. Raw umber, green­ish to very dark brown, grading into black, should contain about 25-50 per cent iron hydroxide and 10-25 per cent manganese oxide (MnO).

Ochre must be mixed with a binder for use as a paint: water i~ commonly used for porous surfaces such as unfired day or plaster; but urine, fat and blood can all be employed. Fat, for example, is better when using red ochre as rouge. Most Attic ochre was probably used for painted pottery: the decline in that industry was contemporary with the near cessation of activity in Laurium around 320 BC.

By-produrls of silver production

Litharge from cupellation may be recycled as the oxidized part of the \melt­ing feed, or may go to a reducing furnace to produce pure lead; or it may be used as a pigment or medicament. Pliny ~ays that Attic litharge was best, then Spanish (HN33, 106). Its colour, basic.1lly yellow, varies with the method of preparation (Bailey 1929,215). It was boiled with .1 starchy substance such as harley to remove some impurities, and then ground.'7 Dilution witi: sJ.It or soda made lighter shades. Experiments following Dioscoride~' medil inal rec­ipes-" produced shades from orange to pale primro~e.

The Ancient Greeks recognized and used zinc (contra Conophagos 1980, 160). Zinc in the silver ore wa~ volatilized during smelt1ng:'" \on~c con­densed on the furnace walls as white zint oxide~. and a littk as metallic zinc (Craddock 1995, 295). Both were collected and processed further"' (e.g. Plin. HN 34, 103-4). Zinc was used fOr bra~s (an alloy of copper .md ZJnc) from at least the fifth century BC. A mudel sheep, 99 per cent ZlilC. 11 d.1!:ec: ltyl!sti­c.llly to the fifth century BC .u1d wa~ allegedly bought/colkc:ed !n A:hens.' 1

A sheet of hammered meta!lit L!!K was found in the Agora, dJtcJ by context between the fourth Jnd ;econd centurie~ BC (Craddock 199_\ 295). Theopompus refers to met,J]!it L~nc ('fa he sliver' Strabo 6!0)_ T~lC name for J z1nc oxide ointment was l11unu/J.\.''

Otba meta!J and mineral_,

Theophrastus (On S!ont.\, .~!I rcrn.nks that othc~ u,cfu! r:::1:cr.d~. >Uch as

130

MAKING MONEY IN CLASSICAL ATHENS

realgar, orpiment, chrysocolla and cyanus, are found in silver mines. He lived in Athens as a metic for about fifty years, and was head of the Lyceum for about thirty-five; the silver mines he knew best were surely those of Laurium. He wrote two books on mines (Diogenes Laertius 5, 44), which have most unfortunately not survived, but comments in On Stones and On Fire indicate his familiarity with the subject. 51

Realgar is arsenic sulphide, AsS, a good red pigment, which is altered to orpiment, As1S,, a good yellow pigment, on exposure. Both were also employed medicinally (e.g. Celsus, De medicina 5, 22. 5). Realgar is an earth formed by volcanic gases and hot springs, and occurs around the igneous rock intrusions of Laurium (Conophagos' map, p and g). Like most mineral pigments, it requires breaking up and washing to remove impurities. Realgar and orpiment are only slightly less soft than talc, and slightly more dense than sand:1' Flaky forms might have been levigated, like ochre.

All agree that what Theophrastus and Pliny call chrysocolla is not what is meant by the term today.;' Bailey and others suggest that they refer to mala­chite, a hydrated carbonate of copper, so although that is a complicated deriva­tion, based on the capaLity of malachite for use, with difficulty, as a gold solder (chrysocolla means 'gold glue'); many copper minerals share that capac­ity. Pliny's explanation (HN 33, 26) of induced chrysocolla production involves the transformation of one mineral into another by water. The ancients' discussions seem to cover several minerals under one name- which is unsurprising, ~ince copper forms a huge group of minerals, over 300 of which are now named_ I gues~ that Theophrastus' chrysocolla is chalcopyrite, copper iron sulphide. CuFeS, which is the chief copper mineral from which others form by expmure. nasion and enrichment. The bra~sy-yellow coating on internal fracture~ of ~ume o;pecimens fits the description 'gold-glue' well; it gives the appearance oi" two p1eces joined by brassy-yellow glue. This identifica­tion, moreover, docs no: presuppose pyrometallurgiul ac.tivity before the stone was named. Chalcopynte is a sulphide ore, found in secondary enrich­ment zones underground. On exposure it decomposes to oxides like mala­chite, azurite and cupntc

Cyanus is w;dely thOL:ght to be azurite, 2CuCO,.Cu(OH),: a blue-col­oured, less hydrated form of copper carbonate than malJLhite, ,;.,ith which it occurs, often on the ,.;me ruck. If chrysocolla i~ chalcopyrite (above), cyan us means ,\zunte and r;c.oiacho w ~ince they occur together and have almmt iden­tical compmltion. th:~ ~e~TH reasonable. It also make~ :.cnse of the ancient division of cyanu~ rn to 'm,1lc' and 'female' varieties. They were distinguished by tone, not colm:: (stdl less chemical composition or mrcroscopic crystal fOrm), 'male' hcir;g_ the J.~:ker variety, 57 so it is wrong to Jdentify male with malachite or nunte ami ttcmale with the other. Azurite c.m vary 'from light blue to a very greenhh blue and concretions of azurite frequently grade into green malachir,·';'' <mlv the bold will assert that the two were diqinguishablc to the gcologJcallv :;ntr.J;ncd .md naked eye oLllltiqum· or today.

131

T_ E_ RIHLI

Malachite and azurite are rich in copper: 57 per cent and 55 per cent respectively; chalcopyrite is less rich (only 35 per cent or so). Laurium copper ores were exploited in the Bronze Age (Gale 1989), and they can still be found. There is no classical evidence for copper smelting, but the argument from silence is weak: chalcopyrite, which melts at 880"C, can be smelted directly without a proper furnace and produces no slag. Similarly, malachite 'can be smelted producing little or no slag in an installation leaving no enduring evidence'; and 'whatever copper mineral was encountered was smelted' (Craddock 1995, 135). With the resources available in Laurium, classical Athenians probably continued or restarted copper production. They may not have obtained all their copper from Laurium, but they could certainly have got some. Apart from bronze production, which requires copper in quantity, and which is in the private domain, Athenian small denomination coins - the khalkous e/4R of a dr.) and krithe C/n) - were of copper and were issued by the polis. If Laurium was not the source of this metal, how was it acquired? If it came from Laurium, then the polis could acquire it by a tithe or stampage duty levied on the private producers who leased the mines.

I know of no literary evidence, but minium (red-lead: Pb,O.) was surely produced in Laurium. It forms as an erosion product of cerrusite and galena when exposed, and varies from bright scarlet to red orange. It was one of the best reds in antiquity: a vivid pigment, supplied by the customer to the artist.'• Its striking colour in the landscape, and its high value, make it improbable that it would have been overlooked. It could also be made from white lead by heating it to around 400 ·c, after white lead h<Jd been made from ordinary lead.

That Athenian-'> were not slow to experiment wi;h and exploit interesting rocks is indicated by Theophrastus (On Stonc.1. 51\-9): allegedly in the late fifth century"" Cal lias, '.1n Athenian from the ~!lvcr mines', invented a pro­cess for manutJctunng synthetic cinnabar, anorhn good red pigment, from the red sands of Ephesus. He collected and experimented upon them, hoping to get gold, but instead found 'false' cinnabar."'

Production subsidiary to extractive industries

CharctJa!

Smelting and ro.l~ting required charcoal. Thcophr ,,,ru '> refers to both pit and mound modc.1 c)t production_'' In the for:-ner. J i':t about a metre square, packed with pnb about 10-15 em in diamctL·: ·~l·..;ms tOr about two days, and cools in Jnothcr two; a large pit ~imdariv ?·llked burns for twenty to thirty days ,l!H~ coob for sixty. In mound hurElng, a mound c. 4 m aero~~ burns for ahou· tour days. and cools for anotiw:- kw before charcoal can be extracted. Eit!~e:· r~~nhod re4uire'i comtJnt w,l'c h. d,ly and night, for hot or

132

MAKING MONEY IN CU.SS!CAL ATHENS

cold spots or holes in the earth cover. Rectification must be prompt if the contents are not to be ruined. Weight reduction through good carboniza­tion with ancient technologies was c. 7:1. Carbonization also increases the calorific value of the fuel: one ton of charcoal has the energy output'J of about 1.65 tons of dry wood and 2.5 tons of green.

To smelt 5 kg of dressed cerrusite ore,M which could make one silver drachma, required on average 2.5 kg of charcoal, for which 17.5 kg of wood had to be felled, chopped, stacked and burnt. The amount of wood for cupelling is negligible.'' Each drachma produced required about 18 kg of wood."

Cupels

Cupels had to be prepared and produced. Marl and bone ash are the main candidates. For marl cupels a suitable refractory clay must be found, dug, washed, fine sieved, beaten well and (if it needed strengthening) kneaded with the powder of a refractory stone or stone-like material: limestone or broken fired pottery were highly suitable. It was then left as long as possible to dry and mature.'7 After the cupellation hearth was shaped, it had to be sea­soncd'B and checked for cracks before use.

To make bone ash,69 bones7(1 must be boiled in water or suchlike to remove gelatinous matter (glue makers would have such bones as a by-product), crushed, and calcined by prolonged heating at 900-1,000 C. Higher temper­atures will cause vitrification, and make the cupcllcss absorbent. The ash is then pulverized in dean water: it contains soluble salts, which arc rcmovtd by repeated rinsing and straining until the water drawn off i~ ta~te!ess. The ash is then dried and powdered, and should idea!!y resemble coarse wheat flour. It em then be wetted, shaped, and tamped into a sha!!ow pit to tOrm a cupel snn.d inches thick.

Other

Other subsid1ary production includes containers, troughs and .,Jed.,, rope. wagons, tmnace stone, mortars and grinding stones, and metal tool.,, die, and Jll\'1;,, ~hey were produced by bao;ketmakcrs, potters, tannno;, wood­worken, ropemakers, wheelwrights, h.1uliers, quarrymen. rna'ions, bron;cworkcrs, ironmongers and engra\'er~. Smiths might wwk \\'Hhln

erga.,ter 1.1. ,J<> at Agrilcza C (Photos-Jones and EI!Js Jones 1994. 355-6). Each of these n~puu uses raw materials (hides, hemp, grasses, reeds, cLly, met,lls and vanou'i woods), which were produced m the area or transported into 11,

a~ raw m.neriab, half-finished or finished products. The p oducts and by-products of Laurium were used by meralworkers

(sdvn, t'.l'i. copper and zin{.), pigmnlt makers (lithJrge. uchrt, chrystxn Ll, tva nus, realgar, orpiment, and r:::nium), drugsellen d:t~largt,

133

T. E. RlHLL

zinc oxides, arsenic sulphides, and copper ores), shipwrights (lead), and builders (lead); local builders used slags and other waste liberally for plas­ters and cements.71

Conclusion

It is sometimes held that the word 'industry' is inappropriate to the ancient economy, as it carries wholly misleading associations of scale and mass pro­duction; 'cottage industry' is permissible. But silver production in Laurium can only be described as industry, much of it 'heavy'. Making silver coins was a hard and complicated business. It required thousands of people, some of them engaged in tough physical effort; others exercised skilled control over nature.

Silver production is only practicable on a large scale. A one-man mine is at least feasible, and if nothing viable was found, the losses were small: up to ten years' rental (perhaps as little as 20 drachmai), living expenses and the opportunity costs incurred. Dressing and smelting, however, requires invest­ment in plant and a sizeable workforce of varying skills, which must all be paid for before any production. Dressing involves preliminary sorting, breaking, re-sorting, grinding, washing, re-sorting, drying and pellcting. An average sized 'workshop' contained a main washery with a three-layer hydraulic cement-lined floor of ,1bout 100 m1

, partially roofed; a o;imi­larly-lined ci~tern of about 300 m ·, dug out of the bedrock, built, or both, and sometimes roofed; various suhidiary roofed rooms, each often more than 10m2

; a large yard; and a peimeter wall with gatehouse. These arc the ergasteria of the forensic speeche•; about mining. They were privately owned, and involved hcary capital expendnurt by either the farmers on whose land they stood, by specialist ore drc.,er~, or mine operators. The vallcvs of Laurium arc littered with such rt.:1m, tn the most heavily indu~tri::diLcC ,!rea~. such as the Soureza Valley, swre~ ~repacked cheek by jowl.72

Xenophon records the three Lrge~t inve~ton in mining leases:-, Ntcias, Hipponicus ,md Philemon ides. w1ric (respectively) 1,000, 600, and 300 <;]ave' Memory of grc.lt achievemen;s ~a rely remembers who was second, never mind who was th1rd; these nu:11bn\ r:1ust have been quite excepnorul.

EstinlJtes ot' the workfonc \".l'\ from 11,000" upward.~. Th~r h :nmc than the number of citizem ln "',!l'-Y po!cis- twice as many a., i:1 Pi~ro's

Jdcal ~cpublic- and probablv n "rt: tiun the total population u+ ,l (:'.OOd few. The workforce needed foor~ l'!:ee were some farms in the .l~t'-'· but r;m~·here near enough to meet thL ,:emand. Supplying food, dav ir~ d,l\' out, for 11,000- wa~ an imprc~siw ~·C,l! ~'vcn 1f most of it was barley·, i: ~~\\~-ten as-.umed that fOod import~. n~WL.,J!iy to Athens, were for the urbar~ popu­lation. hut over 11,000 people 1:1 :he Laurium area produced nn !ooci for themselves became they proli"l~,~ utiler things; that sheds ncv.. .:g::r on 1mponcd foodquffs.

J3.l

MAKING MONEY IN CLASSICAL ATHENS

Silver production was just one of many productive activities in the region (see Table 6A.l); the others have usually been overlooked, as have the provid­ers of goods and services. Their products were everywhere:

Silver- principally as owls, which travelled widely partly because of their reliable purity, but also as plate, jewellery, inlay and other forms of ornamentation; Copper - in coins and bronze weapons, ship rams, vessels, temple grills, door furniture and statues; Zinc - in brass fittings and ornaments, and unalloyed as 'false silver'; Lead- in buildings, ship ballast and cosmetics; Ochre - decorated every painted Attic vase, and was used widely fOr walls, sculptures, faces, furniture and much besides; More expensive and vivid red, yellow, green and blue pigments -were used principally on public buildings and statues; Smelting by-productJ of silver, lead, and copper - soothed and healed the unwell, principally as ointments, salves and plasters.'"

135

T_ E_ R!HLL

Appendix

Reducing !tad orts to metals

Smelting reduces PbCO, and PbS to Pb, lead, in which silver (Ag) and some other impurities remain dissolved. The product is called work-lead (work is required to make it usable), rich lead or stannum. The slags, mainly of sili­con dioxide, iron oxide, and calcium oxide, are discarded or resmelted.

Cupellation isolates Ag from Pb by producing PbO, lead oxide or litharge, which holds the remaining impurities. Some PbO is absorbed by the cupel. This is hearth-lead; it is the saturated bottom of the cupel, and may be resmclted with PbS and PbCO,. Remaining PbO forms a slag which is drawn or blown off; pure Ag is left in the cupel.

PbO slag is made into yellow paint and medicaments, ground up for hydraulic plaster, taken to the smelting furnace to reduce the sulphide ore, or resmdtcd with carbon in a reducing furnace to produce desilvered Ph. The slag from this last operation contains remaining impurities.

Table 6.AI Laurium ores (mmerals worth extractmg)

Ch~miwlformu!d Modern lahmw/ name Modern wmmon name and exp!anarion

l'bCO,

PbS

Pb,O,

Fc.O,.H,O

c:ur~s,

Cc:CO,.Cu(OH),

A<S

i\o <;

-------Le.ld ca~bonate Cerussite*

Lead ,:..!iphid~ Galena*

MmH.::;J Red-lead, a natural crns;on product o! lead ores

Iron hyd~ox:(k Yellow ochre

Copp(·: .'< 1r<w sulphllle Chalcopyrite

H:d. ;:n~ L<lPjlc"!

Ar,,' jli;:C:,

Ar-c:::.:·: 'l:!;}hJdc

CJ"heophrastus' Lhrv><Kol!.;l)

MalJChitc, colour. ~'<"~:1. Azumc Larbon­ate is 2CuCO,.Cu(OH)_.. a less hydrated form of coppn u~:-.o:~ate which onurs w1th malachite_ Coio::c: ~iue. Malach1:e and azurite are nfh ·· cnpp~r (57 pn ce111 and 55 per cem tt,lW< t,\·,·!rl- The copp<'" orcs were explmtec: : o:~· t!:c FlronJ_t Ar.c. for metal and p1r.n:< : ., .'vfal.K!lltt Jll<~ azunte ~ cyanu<o'

Realgar, a red pt~n:c:··

Orpiment, a ydhm ;· :~~=~ .. n•. nml()n product of realr.,,·

"\Ju:t ContJJn> '<mp~·J:•· .J::t~ "".lll<ju.l<tU11e> ol m~tab, notJ6:, [\·~·

136

MAKING MONEY IN CLASSICAL ATHENS

Notes

1 Poletat inscriptions recording mine leases: Langdon in Lalonde ff al 1991, introduction. 2 Ardaillon (1897) surveyed the ancient workings before modern rework.mg obliterated

much of the evidence; Hopper 1968. Conophagos estimaTed that over 10 million tonnes of gangue and slag were produced over an area of roughly 15 km' (1980, 138-44); that must have had a devastating effect on the regwn (Mussche 1994, 215). By classical times such discoveries were pursued by seeking a lease from the Poletai; these are kainotomiai (new cuttings). Hopper cannot 'beheve that the more spectacular shafts are associated With even very profitable mining activities in terms of single leases of the sort we know from the records, still less with prospecting operations' (1968, 320). As he admits (316), some shafts are in stenle regmns; and even 'spectacular' exploratory shafts might be sunk either by those who intended to renew rhe lease (if ore had not been struck, there would be little competition, so the price would remain low), or by those whose behaviour was less than rational: thctr existence is strikingly affirmed in the history of gold strikes and silver bonanzas. Ardaillon 1897, 24-31; he sugge;ts this would have taken tl1ree men working twenty-four hours a day in eight hour shifts about thlrly-six days: an approximate figure, since variation in geology, worker effectiveness. etc, would influence progress. Conophagos suggests about 9.5 m progress in th1rty days (!980, 196) Two can work ;rde by s1de in larger shafts In Eupalinus' tunnd on Samos (only shghtly bigger than the larger shafts, at roughly e1ght feet square). the abandoned face of the south tunnel shows that four men worked on 11: two ahead knelt on a bench cutting out the top of the tunnel; two followed, cutting the bench 1\\d( Vertical shafts are more difficult, bur Two men could work sid<: by s1d~. f,King oppmlle dnecuons. The esTimated rate of progre;s (les1 than 2 em per hou; across the fac~) wa1 so slow that a boy could remove debris with a dustpan during short breaks Hopper 1968,325-6, samples II a and b Theophrasrus On Fm. 21-4 mentions dtggmg but not rc!il:mg Such shafis would have required surveymg above and below to e:Hure ronnecnon. ~,,,. · i•t abdny to handle such lhallcnges is illustrattd 1n Eupahnm' tunnel (R1hll and Tc:, kn 1994). Conophagos (19RO. 116-7) gives 7 per Lent for rqeu10r ... 1:1ci 30 per cent for dtrect smelting; that may g1ve t ou preClse an imprcs1101> of the .1>\(l>l'.'.c:>t procedures.

10 Lew1s 1967, 344. These workers were gennally women anc! dulCrcn_ At a simtlar rate, one person in Laurium could break enough ore to makt 6 drach:Tla> each day (see p.129).

ll This is the propor:w~ wtrh the nches: me that wouiJ ;" ,:,.'I)Pd before smelting, at approximately 30 p<"o lCr:t Pb (Conoph<tgos 1980. ).1J) L~" mh ore, with which the washeries normally dc.tl;. would have mo;c waHe.

11 Various hypothcs~\ for dct,lib arc ig :ort·,: hnc The ::11.i1: ·::ohlems mncern hydrJultc engineering; the fw:r.l'is <t::Jply msu~ icc::• w.1:c' tu gnH·c '1< ·:,,-velocity required m the lint channel to ( .1;rv L'U.Htz I never m nri cc1 :usnc m I!,J;c::.•i ·J.o::« !cs of the commonest s1zes found in \llu (:: '-!_b :1•m) I ill<> tfw 'en~,1:nt:l~ ci~o:1 ~' ·' l:·,! 1edimcntatton bJslns, thus wndering :::us: ul ::~, st~uctute JcC::.nd.ull- :he· w,1:c ,, .. ,_,:,:be clean very early m the system. \'V.Jibc·~y ;!e;~~~· would nut b.l\-e uJnl:nucC :o :; , '" poc.ne such redundam !"· If all parts o( t":lc ,~t'l<~·· were funct"-''la\. \Umc:b:ng " w~u:1g with the stJndard rcconstrucnon. lhe 1::-nplcst (but not nccC"SIJ~dy cott,·ct) "'h.t""' l> that parncles were normally of the ~m"ncr 1:7e now found 1 '- O.'i mm); they l~c·cded to he that stze to get as far as the second d:~n:tel. Jt the c:1d <l wh!Ch 1s tht· ··r1: 1edtmenranon basm. If, however, the puw,Jc ""'-'too !inc, ;JJ:: ,k1 woulc: ,:,li t>c ,~,:Jendcd when the water reached the rei:JJii::~i'- 11::i-.:. unles.1 n w.1, !ct-t to \tJnci Jl''~ :h parudes to settle out

U7

T_ E_ RIHLL

between each processed batch. I believe that the large grinding stones found in situ, wh1ch look bke large versions of traditional flour grindmg stones, and arc sometimes so finely polished as to shine in the sunlight, were used to grind ore to a fine powder, and not (as usually supposed) at the stage of breaking rocks into ch1ppings. Their shallow appearance would have been created by the circular movemenu of a grindstone held in both hands of an operator, in a similar way to the straight-line depressions made in a traditiOnal flour millstone by an operator kneeling at one end.

13 E.g. by Oemostratus ofCytherus (367/6): Crosby 1950,240, no. I!. 54; Davies 1976 no 3623.

14 There is no lmrary evidence, but the small number of smelting snes relative to other types of installatiOn, the multiple fw:naces within each of these few sites, and the specialized skills needed for ;melting all support the condus10n. As for the 'large mining concerns', we do not know what, for example, Nicias' 1,000 slaves did: d1g, dress, smelt, cupel, or some of each, depending on their abilmes and characters. Nor do we know about Sosias' management techniques.

15 The Foundry Patnter's vase (early fifth century): e.g. Healy 1978, pl. 73a and b (pl. _'i I for another furnace); Taylor 1975, 26, fig. 11.

16 Absorbed materials were recovered not just by metalworkers; old refractory linings were also used medicinally (e.g. Dioscorides 5. 178).

17 PbO cannot go m alone, unless one wants pure lead. JR Reducnon is the opposne of oxidation; to reduce an ore mcam ln detach the oxygen

from the m!ncr.,]; fur example, to turn PbO into Pb, whde the 0 combines with other elements 1uch Js carbon (from the charcoal) to make CO (carbon monox1de) or CO, (carbon dJOX1de), or with sulphur to make SO, (sulphur dwxrde). -

19 Charcoal production: 1ee PP- 132-3. Copper smelung consumes vastly more charcoal copper sulph1de ore requ1res about 40 kg of charcoal ptr kg (Tylecote 19.'!0, 188); Merkd found expmmentJ!ly t!w a massive 20-50 kg charcoal wos nced~d per kg coppe (1990, 78-122)

20 Tylecore 191iL _11b I roy ounces of precious metal per ~vonJup01s ton. 1 oz per ton- 30 pa~ts pn tr.1;lwn (p;Jm).

21 A :on~_, 3S,~.i(J ounc~;; .l5,840/600- 59.73 ,-_ 17,000 ppm. Conophagos 1980, 146 foe \"af!obdny ::: rJ:ms Laur1um was rich: the jarosite orcs cxplonrd l1y Romans n; Spa1:1 con:amrc! .1< l:ttk .11 :000 ppm; recently gakna con:.11mng o:1ly 10 ppm would S<' exploned iC:addo' k 199'i. 217 and 211 respect:vcly)

22 'The n1c '." .. :. '.c:.t.Jrt of~ cupel1s that it is suffiuemiv co:ous to aliuw tb, fused ox1dt ·.,\ drJlll into :t 11 ~.1st a' 1t 11 formed. It should be Luge e~uugh to absorb all the liquid, and lt mm1 be -:,.;d\· of Slli:lething upon whid1 The hqUid ~.t; no Lorrosive JCTlon' (Bcrin~c': 192.1. 2-'J

n 5or:Jc sl.tp ~:om Llllrlum contain 2.4 per cen: pilmphu:1r ac1d ;1lus lithuge (Forbc·1 19'i1J.1l2). wha h :nd;CJte> that bone ash wa1 used, Ou: 1!Jg canno: ye: he dated

14 i\L:w i~t 1 'lll7J.19~30 (Geomerm); 19f/h.1;J-.1 (\1;ddk Hdbdtc); 19H4. l ~~ Lttha:g~-,uaked cupels: Conup::,tg"l )l)~t:. ;1IJ:es ; 2 1.1 .md 12. i b

2~ S:J ;}ilL" · ,-~~ :.1o:~i1iws 1dver. Plmy kncw!l·.<t q;~ yn::..:1 !:J~n 1:h·c: h!Jck bw ..!:d ::"· krnw {t'" w:- ·•n: • 'IC~C1:cd m) the reason (f/_\ ii .l:' 1: :1 •.. , 1::1ph:..:r wh:<!l _,;", m"i-.n :;, "c;·, ul ~-:1~l:mg and otrotten egg' ll"''"

lli 1-l: ::' .. ,,! ( n~c :%7. There seems to havr xc:: .1w.: ~::c~' "~ ;u" bv vuLu:i:nll<':· 'J .:~~ci : ,·x, n11V~ f:c·• :; Itt e.g. Strabo 14/i (j:O·--~)

27 G:uu:J<' c .;Jdi~I!O:l ht·anh-bottoms may be ""'t l'""h :'·1: cun::cu,· ·• oJ Ell!> ]o:~,, 'lc.l,:J,;,,i "'lt":t' It was not 'fired' above 8)0 C rPhn:,,-_)onel Jnd Jones 1994, 3~~,_ w:: · 7" ~,~. cc:1: 1'00. lJ per centCaO, and 5 ;1,·: cc::• ~:(). :p )~lf) .. 1:-t<! sm.1!l .mwu"'· OJ ,\:IC"' /;l;;c .1;-JJ aluminmm, 11 nL\1" :H · lc" :c·:::.11:11 n~ <:..jl~k kad-,o.\k' · u ic:L.::L ux.c:c ~ "'1"-'~'>et wnhout carbon d :ox!..;r. '• ,, " ·,: will"T' ::'l:c s~: H:c 1.1 hcJ:nil ·'

138

MAKING MONEY IN CLASSICAL ATHENS

quartz (sand), with the impunti~s remainmg from smelting which the cupel is intended to absorb.

28 'After the manner that cream is blown off mtlk' in a seventeenth-century-AD description (Lewis 1967, 354).

29 Especially when inhaled: 11 would have poisoned those downwind. 30 Lead deposits from ancient smelting are found in polar ice caps; Roman contamination

was worse than at any other period in history (Hughes 1994, 127 and n. 71). 31 The lead-rich cement 'carpet' in Agrileza C, perhaps composed of old cupels, was 75 per cent

PbO(n. 27). 32 Craddock 1995, 202-4 (on copper). Hydrogen in water vapour is a powerful reducing

agent, encouraging unstable CO to form; this unites with oxygen from elsewhere in the melt (notably, from lead oxide, PbO +CO (li) Pb + COJ to become stable C0,-

33 Conophago.s 1980, 332-7 and plates 13.3a and b. Antimony oxide is a good whae pigment which may have been utilized

34 For example, in the Parthenon accounts some objects are called hupargurOJ or hupokhalkos, indicating debasement, and the abtliry to detect it; I owe this to H. B Mattingly.

35 Archime.:le5' non-destructive method of determming fraud by a goldsmith was not known before the third century, and doe~ not work for silver. Silver's specific gravuy vanes - depending on its state (molten, sohd, distilled), treatment (poured ingot. annealed, hammered, drawn into wire etc.) and temperature- from c. 9.5 to 10.7; it cannot be distinguished from an alloy of stmilar 1pecdic gravny by Archunedes' method

36 Rhead and Sexton 1902, 151 and table t"or cMat.l and percentages to darlf)r Eichholt'~ discussion.

37 The only other metal which doe.s .10 1~ Palladium. 38 Sptrtmg can be avmded by very slow cooltng (Powney 1902, 1 0). 39 Lang and Crosby 1964, 24-31; I owe tim rcfercucc to H. B. Mattingly. 40 Conophagos' ratios ( 1980, 343) are u.s~d, rounded after computation. Losses m refining.

now computed at a few per cent (Taggart 194~. it. 260), are ignored. 41 Intermediate stages: '22 hundredwetght o( rtlh (- work) lead with silver at 77 m

troy/ton. This cupclltd produced '!Boo:1 1981. II) 42 Launum tron depos:ts: Ardadlon 1897. !6-li: Snodgrass 1980, Jig 10.2 43 Natural red och1e IS known as powdery !wn:wr~. h. 0,. Yellow ochre i.1 a hydroUI!~un

oxtde, fe_. 0,. H.O: heatmg dnves o:·~·tbt· WJit:. B;own ochre t~ another type o~ ·.:u:-. hydroxid~. 2Fe, 0,. 3H ,0. Launum also ha, deposas of tron sulphide (pyTTtes, FeSJ and iron carbonate (stdc<:te, F~CO,)

44 Cave pamungs are executed in ochres. ''":.tC:ng IJtanufactured red: Schmandt-Bel.lt,.1. 1980,129.

45 6.5 on the Mohr hardne~s scale_ wh1ch r.;::~t"~ !rom l (talc) to 10 (dJa!llond); quJttJ :'-46 Later Juthor1 ~r:1phJIIZt' 1ha1 the grt,1: t'·'"':P" of annquay, such as Apelles, used o·

whitt, ydinw. r~J J::.i !:.b:k (e.g. Plmy /!.\" l' .. 'ill); o: iwr colours seem to have beer: c: c·.nc·c' by tcc!~nH.c!\lCS si:mL::- ·.u poinuli.Lim (w:cc·.,,-,:~ SeurJt) or hy Jpply\ng washes of one ,.,:c:..:· over JI~Othc:, e.g. yt·!iuw over blue f(H g: c"c.: 1( ;Jf,t 1 'Ill!). Natur Jl!j' occurring eJ~thl also!:,,, u::l•zcd. Thco:)h:.mm, On Strm<''. ·::< •::un1 >tveral, including a green one

47 A llm~-consumJ:lg 8:.<XCIS HN .B, 109("x .~.:vs) 41! Hrr/ld! 'i, 96-102 S~t luniler f-IN .B. :nc_q 49 ZIJl( h01b .11 917 C. wdl helow th~ :m·lr:·:,: pntill of ~dver {960 'C). 50 The AthcniJm J:d :mt g1ine the Zlll<- o:c' .!· Lurmm (ulamine or .>mithsonne: Zn( '() )

Jl! z:nc WJS J by-pro,ilH.\ ufsdv<"~ or cu'-':"': ,::1dttng 51 FJtzwoil.t,1r:: Mt:<eu:l~. CJmhndgc. CR ~~~HI! My thanks 10 David Gtll tn:

u:(ormatto:' on :1n, v1pu!llt1h~d obre,-: ... ,, '" D: I' Wilson ottheMusrum br J,

l 19

T. E. RIHLL

52 E.g. HN 34, 132. Zinc and castor oil, famihar to parents everywhere, is the modern verston.

53 For the relevance of Laurium to ancient scientific theories, see Rihll and Tucker 1999 54 Specific gravity 3.5; hardness 1.5-2. 55 It is now used for various hydrated copper silicates - genenl formula: CuSi0,.2H,O;

specific gravity: 2-2.2; hardness: 2 to 4, occasionally reaching 7; colour: turquoise to sky blue.

56 CuCO,.Cu(OH),, specific gravity 4, hardne.1s 3.5-4, colour green. See Badey 1929, on Pliny HN 33. 86.

57 Theophrastus On Stonts, 31. ru Shapiro emphasized (1994, 603), 'Lightness and darkness, or whiteness and blackness, are the fundamental concepts in ancient and medieval color theory and not, as we take for granted, color or hue.'

58 Rosenfeld 1965, 136. Deep blue is next to black in the ancient lmear scheme of colours, and kyaneos sometimes even means 'black' (e.g. Pollux 8, 129, He.1ychtus 4346-8, Sud a s.v. xl>CivrOl). It ts not obvious where light blue fits in the linear arrangement from white to black, but it could be on the !tght side of green, thus splitung azume enher side of malachnc and demonstrating the inappropriateness of colour~ mineraltdenrifi(ation.

59 Plmy HN 35, 30. As often, Pliny points out (HN 33, 120-1) that customers must guard agatnst being cheated: artists could steal this expensive pigment by rmsing loaded brushes and collecting minium fi:om the water Jar.

60 'About 90 years before the archonship ofPraxibulus': r. 405 BC. The expre.IS!on suggest~ that Theophrastus was unsure of hts sourLe. Ephesus was under Spartan control at th11 lime. so hts caution i.1 not surprising

61 Phny lonstantly expounds on man'; tnvemt\'e gemu.s tOr makmg somtthlllg out ut almost every natural thing: even the 'fend excrement' of processing met2ls. HN 34, 171. H 11 histories of processes show that invention and aperimcnt wa.1 gottlg on long he! Ore hi I t1:11e

62 lb<toria P!antarum 5, 9. 4 {mound), 9. 3 l-3 (pa); Olso!l 1991 fd 0,500-7,200 kcal per kg. 64 Conophagos (1980, 352) estlmated 101 d1arcoal requtr<Cd to smell gJiena. wh~<+ n~ed1

m:!y 20 per cent by wetght charw.d, so thts ,, lor Lnrustte, whtlh necd1 ~() ;>er cent O.'i Aholit 33 g of wood {faggot;, not rha:·wal) 11 neeJeJ per 2 kg wu:k-lc~C: ,:u:-1:1g

uq,~lianon. J. ratio of 60:1 feed:fud. Sea1on:nc; the cupel (s~e n. 68) W<'.:i,~ '1ted Jbout a

~m<kctful of charcoal. The figure gtvet~ :1 .m average, rclevam ":ly :,l l.q:c-.lcak c"[Jclltng operations.

60 1:or .1ane commenu on the environmem~l in:pbcatmm: Craddock 199~. ; 'l.l-'i: Rockham ! 996, 29-30.

o7 l'lt~lY !-IN 33. 69on tascomum; Agncnlo kd. Hoow<. 1950) 2.'\0-l; Htrm,c ~'''" :<J90. '! 13 08 f::-~.:i t(n X-10 hours wah about J bucketful of chatco.\l: Bmnguc< 10 : 'l'10. :; 7 O'l R.Hio !988, 35; Percy 1880. 238. 7~) -\l: :1:.:: latrle bones are contamt:~atc.i wt:!: ~~'':~ o.x.de, w!1Kh •s be1t le:• '''-: ,,, :~.\t<

i:g (,onophJgos 19X0,2.'iS-6: P!Jom<;·_l,,u-;.J:H~ H::~Jo:lts 1994 .. '-.\~-'~ 9. l'i.c;-s

72. Co:wnbagm' map 1.1 full btt'. r.o'. ·c~·~~~~,·.ln ·here .tre, to: ex: J". :·.• .• tr'~ed ·"·_, 1:.t:tons near the quJiryon Mnt :•: S:c!.!:'

:; \;·,f ~. !4-15. ContraH the !Jrgcq ot:C~~ k~:uw:: <"lt-lblt.d:mn:ts 1:: 1:,,. ,,, "lt ,:· 110 · .1 ,:,,~ld workshop, and thtny-til~t·c· !.t: :-!1<1\t) ,-- 'sword/hiJJ,. wn:,,,, '':' Xt ~UP!:nn

,,,,·~:,:hat all h1s contcmporartt"> u;,·o;vt·c! ... ·1::::mg qjJ they ~:,·n:"· ""<l:c "'len Jt:J ' .. ~;OYt'd as many as poss1ble: I'M ..:, ~- h

{ :n~wphagos' conservattve ~snmatc ( 19SO, ,!- !~)

7:'> f).;; ln wa~ the staple slave lond; b:-kv ~~t.:~i · 1.1y ilJt't been th~ n:.J :1 ,' ,. ·,_,., . ._: J!ld ate better, .some Cf!(,!Stc:~ ·r·.Cl,. · <iiiJ,,·mr:

140

t"J'. OJ!J~r~

6

MAKING MONEY IN CLASSICAL ATHENS

T. E. Rihll

Introduction

Laurium is justly famous for its silver; less well known is that about 16 kg of ore had to be extracted and processed to produce each silver drachma, weigh­ing about 4 g, or that the quantity of food which had to be supplied to the labour force engaged in processing minerals in Laurium probably amounted to at least 4,000 kg per day. Moreover, Laurium has many other mineral resources which were explored and exploited in antiquity. Athenian pot painters, for example, depended on Laurium for the pigment which col­oured the pots red and black.

Laurium is part of Athenian history- and not just Salamis and immedi­ately before. Mining and ore-dressing represents by far the largest scale industrial production in classical Athens_ Archacologically there is nothing to compare with the Laurium valleys, which arc packed with shafts, grinderies, washencs, CISterns, quarries, furnaces and slag heaps, from high in the hills to the coast. The number of men involved far surpassed those in any other productive activity except agriculture. The Hate took great interest in this industry, about which it drafted law\ ..tnd recorded various details; thus we have a type of evidence we lack for other crafts. 1

Silver production

Much here is mnjcctural; almost every sentence ought to be qualified by 'per­haps', 'possibly' or 'probJbly', since we r.neiv have direct incontrovertible evidence on deuik However, the btl tude to: ~peculation m the history of technical )Ub]ect~ i~ more rircumscnbed th.;:l 1n '>Oci:~l or political matters To transform m;:-~crah intu metals requires ccrtalll conditions and proce­dures without n:wiction of time or place. \1cthods described by Pliny, for example, are repeated over !,000 yens Lltcr by Agrimla. The reconstruction of practice at Laurium j, ba,ed largely on c\·idcncc drawn from different cen­turies and countrle\; but room for m:~nocuvrc lS strictly limited by geologi­cal, physiul and chemicai 'iaw~'

1 ;s

T. E_ RIHLL

Mining

The ores sought were principally cerrusite, lead carbonate (PbCO, ), and to a lesser extent galena, lead sulphide (PbS). Both contain lead (Ph) and a little silver (Ag). The proportion of silver to lead in these ores world-wide is normally a few thousandths of 1 per cent. Good Laurium ores were about 2 per cent silver; these deposits were worth extracting. The scale of extraction was considerable:2 the combined length of the galleries in Laurium was some 140 km.

The oldest mines follow these minerals wherever they go from the sur­face. The discovery was probably the result of luck, observation, local lore about peculiar pockets of land, and knowledge about rocks (Rihll and Tucker forthcoming). The valuable mineral in its recognizable unweathered state might be exposed through ploughing or the uprooting of a tree, for example, but an observant eye had to spot it. Prospectors prob­ably sought out areas where, according to the locals, the vegetation or water was 'odd', or where animals would not go, or where the earth was a strange colour, for example.) Cerrusite docs not look like a metal ore in the obvi­ous sense of having bright shiny bits running through it, but it can look like litharge, a dirty-yellow by-product of silver processing, which was added to the smelting charge or processed to obtain other materials (sec p. 130); this probably inspired attempts to smelt it.

A mine dug into the hillside following the vein of ore is a drift mine. Expe­rience or oprimism guided prospectors to sink exploratory shaft_~· or cut gal­lenes mto barren rock to find new lode~ underground; the latter arc cross-drift mines. Exploratory cross-drifts were normally abandoned :tfter 12 m if contact had not been made.' Shaft~ go more or less straight down; Ardai!lon (1897. 25) estimates that s1x men working in three teams· '-"'Ouid have takm two years to dig 100m down (deeper than most shafts, ti~ough a

few arc deeper}. Tools were iron chisel, hammer, lever, pick, and wedge, ten-hour-burning 'dumpy' Laurium oil lamp, bucket (probably leather), and -where space permitted- a wooden sledge to drag ore and spoil out_ W..:.tcr or v1ncgar Wa\ used to douse a rock Lee fractured and split by fire-\ettJng. The u<;e of vinegar has been for long a pualc, but may be explained hv the beilef thJ.t 1: prevented rcignition (AeneJ.~ Tacticus, 34). Its use 1n tlw f-(Jurtll centur\' 1., implied in Thcophrastus, On hrc, 25 (immediately after J p.1~;,1gc on :n:n::1g) .1nd 59. Strabo metltlom it, along wtth mud, alum or [y··ci- 1 J:l1C~.

as ,J frc L"Xl :Jguisher for naphtha. agal:l'>t wh1ch W.lter i~ \,Jid :o ;,c wnr,e rhan i:>cic'-'· in an unedifying talc abo',__!: Alexander (74_l)_ Samples ,1! 'ipOli

collcncd hy f-lapper and examined bv J gco]og;<,t showed sign<; n: h.n·:ng been l~c.ncd

The •;izc of <>hafts and galleries i~ luge n;ough ,\t least to allow t ·-.,~>1pcd

PJ.'>\d!',e b,· o:Je person (Fig. 6.1), .md Jt n:oq to cxrract the lode wn!w,:' c.JU'i­

ing t l1ll.1p'e [! nece.~sary, pillar'> of good nre wcrl' ldi untouched '!'od

: i6

MAKING MONEY IN CLASSICAL ATHENS

Flxur<" li. I Ti't :1~a111 gallery in the mine next to the theatre Jt Thonkos

Wds PJ'k't~ into excavated part~ of a chamber, to support the roof I"h· chid factot~ Jctcrmining the extent of a mine were the presence of ore and brc,Jth­.Iblc Jir, Jnd the absence of water flooding the working face (not a prohlc!~1 in LauriL:m). Some shafts were dug, and others refilled, solely to !rll~)rovc vcntibtion.'

\1.\ny n:lltures failed because they did not find enough ore to be v:.1:)ic. \( ore \\,t'> !ou!ld, extracted rock was first wrted underground_ Am· ''' ll:c a\.'>C.>•,cd :1rincipally by weight relat1ve to ~ize in the hand, s:1H :.' i!ght w:r' poor-- .1' lcs~ than about 1/Li 'leJd WJ\ di\carded unJcrgrm::·,: :'<":-,,·­bk or !c:-:-:oycd to surface spoil heap<, it nor

A1:y il,n:~J a•;sesscd as more than about 1j;; lud was broug,ht :n ;!~' ::J(l".

1-vhnc :r w.11 .1~sessed by eye as well as hand. Anyrhing identificC .11 ""O:C d-:.1:1 on..:-third kad was smashed into pea-\ized pieces and sent stra!t-h~ tel: ~:nc!t­

lng In_ 9) The rest was sent to J.n erga~terion to be 'dressed', to ,_·:-;,,we·'" r~1t:L-h ur:w.nHcd material as possible before smelting, whJcl-: w.~, ,~-:·~( c;h .md C<J5' i\'

117

T_ E_ R!HLL

Drtssing

In the ergasterion (Fig. 6.2) the ore was taken to the grindery, which con­tained one to four large, hard mortar stones. Here it was hammered, to break it into chips and pick out the obvious gangue (rock matrix); that removed about 5 per cent of the material (Conophagos 1980, 343). Breaking rock is extremely hard work - hence its common association with convict hard labour. In the latter half of the nineteenth century a good (free) worker could break by hand just over 100 kg per day. 111 The ore was then pulverized in hand-operated mills (hoppers).

The powder was taken to the washery to remove as much dross as possible before smelting. The importance of this stage cannot be underestimated: at least 60 per cent (by weight) of material brought into the washery was dis­carded here. 11 It is by this process that the Greeks were able to make metal from lower grade ores, which are much commoner than the high-grade ores with which metallurgy began (Craddock 1995, Chapter 5). By hydraulic action, the denser galena (specific gravity 7.5) or cerussite (sp. gr. 6.5) settled nearest to the washing table, and the lighter dross and quartz (sp. gr. c. 2.5) was carried off to settle in sedimentation tanks, while increasingly clean water flowed round the circuit to the rcbailing tank for reuse. Ore was thus concentrated; if necessary, the proce~~ might be repeated. There are problems with this reconstruction, but they need not delay us. 11

The concentrated sludge was plied on the drying table, where water drained off into the channels; sun ,;nd wind drove off remaining dampness. The ore was then pressed into pcl!cb with a flammable binding agent such as dung (in heav1ly industri.1lizcd Ll<!rium. human dung would have been the type most widely available), anJ d:1cd for smelting. Without pelleting, the powder would h .. we smothered ;i,,, t\rc 111 the furnace: modern powder fire extinguishen work on this prinu~):(,

The gangue was rcmoveci from ·:"c snc. Large quanti tie~ were generated: what happened to it is uncleJr_ .'!once. but relatively little, went into hydrJu­lic cements and plasters for w.H~K:\' w,dls and floors, cisterns, channels .1nd other wet areas such as bathnwrw •. wh1eh .1 few ergastcria contained. Some, but agam a tiny proportion, we;;· !!~to mud bricks. Much WJS pcrhap~ thrown down old ,haft<>, ,J> Ill qr<"' !ZC Age Siphnos (Gordon Davie~. ;1er~ wmm.); thJt m1ght expL1111 th· ·:": -..:p' (tmaJaxima) label for ~ome mines

-~ mt'!ting

The poli., nude money f~p:;: ·· ru~ (Xcnophon, De Vattgalilm> 4. 49), though how i1 not dear: pc: :1 ::•, · ""<High a tax. At least some furnace> were ?rivately owned, 1

' and they we:· :1· ·t-->,Jhly built and run by specialist ~mclt­l"t) or brge m1n1ng con\t'Jll\, >11 ,1 much more limited and ce:Jtr,tim::d !J.J\1~ tlun ore-dro~1ng 1!1-'lt,;!!.!· l1:' ~~~1elting was and >till i> J h1ghlv ~kdled

: !8

MAKING MONEY IN CLASSICAL ATHENS

/"".. jCistern Well '-...__/ • •

{/"""~•-....\

\......_ ___ / COllapsed subterranean cistern

Washery

Gate for entry & exit

20 metres

Scale is for guidance only

Key:

1 Waterproofed walls and floor 2 Floor crusted and stained with ashy material 3 As 2, plus traces of iron working and hearths: smithy for

tool production and maintenance?

Fq:un 6.2 AgnlezJ 'C' erg,15ltrln:-: 'i:c ;,!Jn (after Jones m Photos"Jone; and Jon~; !994 pa."·im)

119

T. E_ RIHLL

!·r_~11YI' 6.3 Furnaces Jt 1\•::nrm<" near PountJzeza

120

MAKING MONEY IN CLASSICAL ATHENS

job, but it is also dangerous and unpleasant. The few surviving smelting sites had five or more furnaces side by side (Fig. 6.3). Raised platforms at the rear indicate that they were several metres high, much as a famous illustration of a bronze-worker's furnace 15 suggests.

It is unsurprising that few furnaces survive: unlike most structures (e.g. kilns, buildings, harbours, or washeries), they have a very short life. They are designed by men trying to reproduce what happens inside volcanoes: they melt rock. Molten rock is incredibly caustic. Few substances can contain it at all, never mind for long. Hence furnaces have continually to be built, demol­ished- to recover valuable metals and minerals absorbed by the furnace itself' -and rebuilt. The development of good refractory materials, to line the inside surface, and hearths, to hold the molten metal, remains challenging today.

Cerrusite, the main ore exploited in Laurium, can be smelted directly. Galena, however, is a sulphide ore: to produce metal, the sulphur must be liberated by roasting, i.e. cooking with charcoal in an open atmosphere, for example in a trench. Then it can be smelted normally. Roasting and smelting can be done in the same furnace if oxidizing conditions are provided in part of the furnace (top or bottom), by pumping air in at that point, and neutral conditions, with moderately limited air supply, elsewhere. Roasting occurs as the temperature rises to 600 ·c; beyond 750"C, smelting starts. Roasting and smelting in the same furnace would require enormous skill and experi­ence to do effectively; Conophagos supposes that it happened at Laurium, but there is no evidence.

Concentrated ore pellets, chunks of litharge (PbO) from prior smelting (seep. 125), and chippings of high grade ore straight from mines, could be loaded in the fu:-nacc singly17 or in combination, in alternate layers with charcoal. Cerm~1tc ore~ require half their own weight of charcoal to reduce. 1 ~ When the ore i~ plena. the charcoal merely creates and maintains a suffi.. cient temperatu ~:..:.but it plays no part in the chemistry. Thus galena requires much less charcoal: about 20 per cent by weight of orc_ 1 ~

Thus charged, the furnace was fired. At temperatures of c 800 ·c, lead oxide reduces to :11etallic lead, and the stannum (work-lead), which holds the silver, form~ .wd flows down through the contents of the furnace to the bottom; the :ap-hole was probably permanently open to allow it to flow out (Fig. 6.4). r~L" high density of lead helped p.nti,dly melted pellets con­taining impuri::~·, {which are lighter than lead) to f-loat Js slag at the top of the melt. A' ;t t.:>nc out floating on the lead, the •dag was skimmed off, probably witi-: a:: ::-,m implement (e.g. Pliny, H,:,·ton,l Natura/is 33, 35), and was d1rected ::no J •dag pit, while the work-lead flowed into another p!t, both were lef: to Lou! The solidified puddles (ukes) of work-lead were then cleaned ofsurfau: debri'i, broken up, and removed to a cupellation furnace to isolate the q]\·~·r. Enough silver and lead was lost with the slag to just1f)r resmelting b~ R;• ~~Jm (Strabo 399); their slag~ were in turn resmelted in the nineteen+ t( 'ltury

121

T_ E_ RIHLL

"' 2 metres

Scale for guidance on'Y

Figurr 6.4 Smelting furnacts (rtconsuunion)

Cuptllation

The proportion of silver to lead in cerrusitc and galena is normally a few thousandths of a per cent, usually expressed as ounces per ton to avoid 'the small number~ involved when the preuous metal content is expressed as a percentage. 1 oz per ton is roughly equal to 0.003 per cent'."" Good Laurium orcs were L 600 oz ~ilver per ton kaJ: about 2 per cent silver, or 1:60 silver:lead.-' 1

Cupellation involves considerable ~kilL If galena is dropped in a fire, it will reduce to lead; if it is left longer, the lead ox1d1zes fully to a fine white ash, leav­ing a miniscule bead of pure silver. Cupellation separates the metals on a viably large sc.de, more quickly th<n: on a:l open fire, and with less lms of silver, by contro!ling and contaming the heat, and having a porous, chemi­cally inert hcJ.rth: a cupcl. A cupel is .l lined hole in the ground or in a ra1~nl hearth; the lnung 1~ the cupel. The matenal OlliS! be rcfrJctory (able to stanJ the caustic conditions), porous, chem1c.dl;. i:len to the substances to be melted in it, and abwrbent. 22 Suitable mJ.reria], .1re bone J.sh (calcium phosphate). wood ash, marl (a mixture of loose, impun· l1mcstonc and clay or sand), p!J.~­ter of Paris (pJ.rtiJlly hydrated gypsun:). or refractOI)' day with or withuur powdered unglazed pot~_'' The heat 1., llipplied by surrounding tire, f.lllllL'ci vigorously by bellows

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MAKING MONEY IN CLASSICAL ATHENS

Laurium cupellation furnaces are a matter of conjecture: none has been identified. They must have existed to produce silver: until recently there was no other method. Cupellation debris is distinctive, and has been found. 24 A furnace could have been a shallow hole in the ground, lined with several inches of hard packed powdered marl or bone ash mixed with water, and covered with a clayey dome with holes for wood faggots and bellows and the insertion of work-lead and rods to remove the litharge (Fig. 6.5). Such hol­lows are not easy to find, especially in an area littered with substantial indus­trial remains. Cupdlation may have been undertaken well away from smelting, because sulphurous gases, which galena smelting produced in quantity, tarnish silver. The tarnish, silver sulphide, forms on the surface of the metal when it is exposed to sulphur.n

The cupellation furnace was fired empty, perhaps at night or in a poorly lit but well ventilated structure so that flame colour and furnace interior could be better seen. The temperature inside must reach over 800 ·C: lead melts at 327 'C, but below SOO"C lead oxide forms as a crust and 'freezes', preventing cupellation. The silver does not have to reach melting point; indeed, if it does, some will be lost through spirting (seep. 127) and volatil­ization: i.e. some will burn ofe' A cupdlation furnace preferably has a tem­perature between r. 810"C and 950 ·c; this could be judged by sight, smell. radiant heat, and experience.

Once the temperature was high enough, cakes of work-lead were pushed in to melt. Throughout, a fume rose as some lead was vaporized. Air forced in by bellows acros~ the pool of metal caused the lead to oxidize, and this would have fOrmed litharge, 'which at the temperature of its formation is a liquid' (Beringer 1921, 110). A good cupel ab~orbs this as a ~ponge absorbs water. A~ the litharge drams away, fresh lead is exposed to the air, and the proce'>'> con­tinues until, ideally, all the lead is ab~orbed. Invariably some silver will al,o be .lb.'>orbcd: more if the temperature get'> too high, or if the cupel mater:d! i, too coarse and pervious to the metal as well as the oxide (Powney !902, 43-4). More cakes were inserted until it wa'> judged that the cupc! wuiJ absorb no morc.2

;

Surplus and viscous litharge on the surface of the melt, known as 'scum of silver' (e.g. Plmy HN 33, 106), could be blown off by bellows'' or '>km~med at"! W!th iron rod'>, but this was not ne~ess.1ry: if heating .md oxidizing coc­Wluc~. one gets pure lead oxide, a fine whlte powder which would blow ,;w,n· Th, l'> pwbably the solution to the prohlem of what WJ.S done with mmr u: the loci by-products of silver produu:on (about 2 kg lead per 4 g ~1lve) notlm:f!: The 'missing' millions o( tom of lead simply blew away J'i ~ fi:h' toxic J.sh, to contaminate the local'''- even the global- environment

When the operation was complete, when hardly any litharge was bein~ prnduced and the melt surface turnC'd f:-om yellow (indicating lead) to wlll'.c (1nc~:u:mg silver), the bellows were otoppcd and the fJggots removed l'hc <;Jl\·,,~. which ideally (to prevent spi~!inc'- .1•1d unnecessary los'>) would k ,o(·

!2.1

T E. RJHU

1 mBtre

Scale lor guidanal only

PbO

Fig1111" 6.5 Cupel!Juon Ji.nnJcc (rcconslru<.tnm).

but not molten, was a puddle in the litharge-soaked cupel. The btharge solid­i fie~ on cooling, absorbed wit!11I1 the cupel J.nd enumted on it~ inside sur­fJ.ce; in this state it is hearth-lcrtd. The silver cake, when cool, was removed. On the bottom of it was hearth-lead, which was chipped off and ground up to reprocess in the smelting funucc or purify into lead; on the top of it were fragments of solidified lithJrge, which were chipped off and added to the !ith . .nge which was ~kimmcJ or blown off during cupcllation

A bone-ash cupcl absorb up ro about 75 per cent of its weight of lead oxide; J marl cupel i,l usuJ!l!· it-,~ dl:Ccivc, but ancient tXJ:1:?ic' .nc mas­sively er:crusted wtth lithJrge .!lld served thur purpose well.' To rerovcr this lead. and any '>liver lo,-.t wnh it. required the destruction of the cupel: it was smashed and .~ifted, to sepJrc~re rhe Jb~orbcd hearth-lead !rom my uncon­tamin;Jted marl or bone J,<;h: the hearth-lead is added to that chtpped off the bottom of the silver rake, .md goes to the 'melting furnace (perhaps after concentrJtion in a washc-r\"): unco:HJminJted marl or bone .1sh i~ reused to m.1kc JEother cupel

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MAKING MONEY IN CLASSICAL ATHENS

The effectiveness of the cupellation can be assessed by eye; experienced workmen would have known what to look for despite ignorance of what the impurities were or how they had their effect. If silver or cupc! looked wrong, the silver was recupelled or, if it was very bad, resmelted.

The silver cake should look like a slightly flattened elliptical button with an evenly rounded appearance. The upper surface should have faint mark­ings as if it were crystalline; if it is also dull and grey, and lacks silver's charac­teristic lustre, platinum is present. If the button is very globular, or more rounded on the lower than the upper surface, lead is still present. If it is spread out and adheres firmly to the cupel, there is copper: the cupel touch­ing the metal will be almost black with copper oxide.

The stained portion of the cupel should be straw-yellow when cold; it will be if lead is the only easily oxidizable metal present (Beringer 1921, 100). A white to lemon colour indicates significant quantities of arsenic, while a greeny-grey to black stain indicates copper. Cracks, together with an indis­tinct margin (so that the cupel appears to have unfolded) indicate antimony. If the cupel is not just stained but also corroded, a yellow ring indicates zinc, dark green indicates iron, while blue-black indicates manganese. If the cupel shows any of these in quantity, recupellation or even resmelting i~ nece~sary.

Litharge could be utilized in several different ways. That scraped or blown during cupeUation could be reduced to pure lead in a moderately reducing furnace; that is, a dosed furnace with plenty of carbon (charcoal). The oxygen in the litharge combines with the carbon to fOrm carbon dioxide, !caving pure lead (2Pb0 + C ...;.. Pb + COJ If Pliny's figures are accurate about a quarter e/9: HN 34. 159) of the lead will be lost through volatiliza­tion and absorption into the cupel. Alternatively, chunks of litharge could become part of the feed fOr the next smelt, which was pJrtKularly likely if galena was being smelted: lead oxide (litharge) reacts wlth lead sulphide (galena) to produce lead and sulphur dioxide: 2Pb0 + PbS ...;.. Wb-+ SO,. Ancient smelters did not know this as expressed, but would have 'know1~' that adding litharge to an unroasted galena charge had beneficial effects. Litharge could also be utilized as a pigment or medicament ('>ee P- 130).

Hearth-lead, although composed overwhelmingly of litharge, was the part of the melt which had absorbed most of the impumie~ ... uch as copper, anenic, antimony, iron. bismuth and zinc. If, like the h!:a~ge scraped or blown from the surface of :he cupellation melt, it was res me! :eC on its own it would produce a much h;uder, more 1m pure lead. Thi., w.l'> not necessarily b,1J: pure lead is too soft tOr mmt pr.1ctical purpose~.

Hearth-lead could imtead. !ike litharge and for the ~anw ~cason, become part of the feed for the :1ext >melt. Altnnatively, It WJ\ ,omctimes partly purified by poling, a techmque developed in copper smeltn1g: green wood thrust into the molten metai vaporizes on contact, creaung_ Jouds of steam, hydrogen and carbon-nd1 g._l'ie~': In molten copper, this cnLKe~ J.ny copper oxides present into mc~.dhc copper. In molten lead, d\"'l,J:''lc vaporization

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of green wood reduces lead oxide to pure lead, while some of the liberated oxygen combines with any antimony and arsenic present to form oxides which, having a lower specific gravity than lead, rise to the surface where they can be skimmed offn

The final products were pure silver, litharge, and pure lead. Undesir­able by-products were various slags, and furnace gases, for example sul­phur dioxide, which would have filled the vicinity with the smell of bad eggs.

Assaying

Assaying is the 'art of finding by ready methods the proportion of metal in an ore or other substance' (Percy 1880, 699). It was common enough to be used in philosophic discussion: 'Justice is like silver, and must be tested by the as sayers, if the genuine is to be distinguished from the counterfeit' (Aris­totle, Rhetorica 1375b). Plato's musical assayers accept satisfactory songs, reject the unsuitable, and insist on the revision of the defective (Law.r 802B). The purity of silver was tested by Athenian and foreign sceptics, traders, bankers, metalworkers, rl a!." The Dokimastes was a public slave who tested the purity of coins: the officral assayer.

We do not know how the metal was tested. 15 Methods known to Theophrastus (On StoncJ, 4"i-7) were:

'Fire': this could refer to vi~ual assessments of the silver button and the cupel through cupcllmg J. small sample, or to spirting (see method 6, p. 127), or to ~omnhing else.

2 The Hcracleian or Lydian stone (the touchstone). The Lydian stone is a black flinty jasper. but other close-grained, hard, flinty, black or very dark slates work too. \X1hen mctJl rs rubbed on such a stone, the experienced eye can tell ti-om the colour of the streak approximately what proportions of gold, silver and copper are present. Four basic proportiom of alloyed gold can be distinguished even without the stone: silver:gold; 2:1 silver:copper; I: I silvcr:copper; and 1:2 silver:copper (Rhead and Sexton 1902, 147)

In recent t1me.,, a~~JV !)\' touchqone used up to thirty set~ of needles of known proportioc,, rl:e <,c: ne,lfest in colour to the tC'it material wa, employed as ,l (Ontrol h rubbing both on the toudutonc, and comp.lr!ng the control with the re~a 'rreJh_ Theophrastm (46) say' that wme:hing simi· larwas done for golJ ctnd sraren. Reconstruction of the text (Eichholz 196\ 118-9) produce<, a ~(ale'" wlm.:h gives proportions comparable with recent mage, enabllng diffncnu:s of 1/1 carat to be distingUished in gold and gold alloys. I have ~"lC"l'!: ~:~uhk tu discover if the touch.~ tone can tcsr sdver and silver allov<; i:1d.:-pc::den:iv of gold.

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MAKING MONEY IN CLASSICAL ATHENS

Additional methods known to Pliny (HN 33, 127-8) were:

3 Place a silver filing on a red hot iron shovel. If it remains bright, it is pure; second rate rurns red, and anything that turns black is rejected. This test, says Pliny, can be cheated temporarily by soaking the shovel in urine. The colour change results from the formation of oxides of other metals, if present. Urine works against this by acting temporarily as a reducing agent, thus preventing the formation of oxides.

4 For a polished sample, breathe on it and look for immediate fogging and rapid condensation. This results from the excellent heat conductivity of silver.

5 Beaten and polished plates of silver reflect images. This property is reflected in the modern mirror, in which silver is applied to the back of a sheet of glass. Pliny says that this test can be circumvented, but does not explain how.

[Aristotle] (Problcmafa 936b) implies another method:

6 'Why is it that water when it boils does not form a scum, as do pea soup and lentil soup? And yet water is lighter than these, and light substances ought to be able to project themselves more easily to a distance. The same thing happens in the case of silver when it is being purified; for those who clean out the mint make gains by appropriatmg the remnants, sweeping up the silver which is scattered about.-. substances which have body in them, like thick soups and silver ... contain much ;.:orporeal matter and offer resistance; they are subjected to violent force as the heat tries to make its way out and forms bubbles wherever the he,lt prevails; for, owing to their density the heat cannot pass through them, but the density prevails until it is thrown off by the heat which flow., into it. The result is a sudden impact, and not a continuous pressure, owing to the heat passing up quickly from below' (trans. Forster).

This is spirting, which is caused not by dcn~ity but by oxygen. Silver, if heated to around its melting point, absorb~ brge quantities of oxygen at atmosphenc pn·\sure.'' _lust above its mcit:;1g p01nr, silver can take into solution about ten times it\ volume of nxygc:1 to ~aturation (Butts and Coxe 1967. 126). Thi~ oxygen is di~sOl\'cd !:1 :lw molten metal rather like carbon dioxide 1~ di_,_~olved in fizzy drink>, though in the latter case it occurs only ur::der pressure. When the bottk 1~ opened, the carbon dioxide emerges from ~olution, forming bubble\ wi:1ch e~~capc, creating the charac­teristic fizz. A more energetic reaction onw> in silver. As the metal cools, the oxygen IS libcr Jted v1gorous!y before solidi ilcation, cau.~ing the melt to 'spirt'. Su~,det'.ly the crmt breab, and ox\·gc:; an~! particles of molten metal burst out.

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T. E_ RIHLL

Impurities in the melt will unite with any oxygen present to form oxides, and thus reduce the oxygen available to spirt (ibid, 1967, 304). Thus spirting can be exploited by an assayer. Impurities reduce the spirt to something better described as blistering; more than 2 per cent impurities eliminate it. Athenian coins reached at least 98 per cent purity (98.5-99.7 per cent in all tested examples); that suggests spirting as the most likely method of assay. Since heat is the only 'tool' used, this is probably assay 'by fire' (method 1). Official assaying presumably took place in the mint before coining.

Coining

'A Greek mint must remain for us a murky workshop', Starr correctly observes (1970, 78). Silver buttons, we assume, were broken into grains, which were weighed to the required denomination (ideally 4.37 g for a drachma). The con­sistency of Athenian coinage presupposes scales for weighing small quantities; since all money--changers depended on scales, they could pivot (if not weigh) finely, even minutely. Grains were compared against official standards, but one or more coms- not necessarily in mint condition {Vickers 1992, 68; 71-2) - might have been used instead.J" The grains were then placed in something like an egg holder (a round flat plate with round depressions in it) and heated to make flarH: ju~t below melting point, pieces of silver are so soft that if in contact they stick together (Percy 1880, 5). F!ans were ready for punching when cool and ~olid enough to handle.

Quantities

For cakular:uns of the material worked to produce one silver drachm,l see Table 6. J

A con<:.w~ .,., ,1vailable. When the lease for ,1 Carmarthenshirc silver m1nc, with simd,Jt ore (galena) and technology. was challenged in 1623 AD, the smelting of) tons of concentrated ore produced" 85.5 oz of fine \ilvcr, :md 18 cwt ofk.H!. These measures give rat1os of ore toncentrate: sliver of 1143.1. and ore l(Jilccntrate:lead of3:1, which arc very close to those ofConophago~ (1140:1 .tm! ?.88:1)

Related production processes

L.1unum :n"'iuccd more than silver; it I'>,\ poly;nctalltc region .. 1::d illJ\' he explottc'~ Jg.1:n. for zmc and iron (Conophagm ~980. 54). Its orcs .d,o <llll­tain Jnt:;•:ollv, arsenic, copper, and gold, wi:1ch were rccognizni ;n J!IC!Lj­uity, a nO :h.1:imm, cadmium and bismuth, which were not. Silver e>.tractwn wa~ the r~:-i 1l!p.d il1c us of endeavour in Jntlqutty, but other l1lillC-,~L, .1:1d by-p11'dc:, ;-, 1!: .\ilver production were rCl(lgn:Lt.:d J'> u~cfui. ,1::c! ciuh pnll ,·,,c, ·

128