Basalt

For the World War II raid, see Operation Basalt. For thecities, see Basalt, Colorado and Basalt, Idaho.

Basalt (pronounced /bəˈsɔːlt/, /ˈbæsɒlt/, /ˈbæsɔːlt/, or/ˈbeɪsɔːlt/)[1] is a common extrusive igneous (volcanic)rock formed from the rapid cooling of basaltic lava ex-posed at or very near the surface of a planet or moon.Flood basalt describes the formation in a series of lavabasalt flows.

1 Definition

Columnar basalt flows in Yellowstone National Park, USA

By definition, basalt is an aphanitic (fine-grained) igneousrock with generally 45-55% silica (SiO2) and less than10% feldspathoid by volume, and where at least 65%of the rock is feldspar in the form of plagioclase. It isthe most common volcanic rock type on Earth, being akey component of oceanic crust as well as the princi-pal volcanic rock in many mid-oceanic islands, includingIceland, Réunion and the islands of Hawaii. Basalt com-monly features a very fine-grained or glassy matrix inter-spersed with visible mineral grains. The average densityis 3.0 gm/cm3.Basalt is defined by its mineral content and texture, andphysical descriptions without mineralogical context maybe unreliable in some circumstances. Basalt is usuallygrey to black in colour, but rapidly weathers to brownor rust-red due to oxidation of its mafic (iron-rich) min-erals into hematite and other iron oxides and hydrox-ides. Although usually characterized as “dark”, basaltic

rocks exhibit a wide range of shading due to regional geo-chemical processes. Due to weathering or high concen-trations of plagioclase, some basalts can be quite light-coloured, superficially resembling andesite to untrainedeyes. Basalt has a fine-grained mineral texture due to themolten rock cooling too quickly for large mineral crystalsto grow; it is often porphyritic, containing larger crystals(phenocrysts) formed prior to the extrusion that broughtthe magma to the surface, embedded in a finer-grainedmatrix. These phenocrysts usually are of olivine or acalcium-rich plagioclase, which have the highest meltingtemperatures of the typical minerals that can crystallizefrom the melt.Basalt with a vesicular texture is called vesicular basalt,when the bulk of the rock is mostly solid; when the vesi-cles are over 1/2 the volume of a specimen, it is calledscoria. This texture forms when dissolved gases comeout of solution and form bubbles as the magma decom-presses as it reaches the surface, yet are trapped as theerupted lava hardens before the gases can escape.The term basalt is at times applied to shallow intrusiverocks with a composition typical of basalt, but rocksof this composition with a phaneritic (coarser) ground-mass are generally referred to as diabase (also called do-lerite) or, when more coarse-grained (crystals over 2 mmacross), as gabbro. Gabbro is often marketed commer-cially as “black granite.”In the Hadean, Archean, and early Proterozoic eras ofEarth’s history, the chemistry of eruptedmagmas was sig-nificantly different from today’s, due to immature crustaland asthenosphere differentiation. These ultra-mafic vol-canic rocks, with silica (SiO2) contents below 45% areusually classified as komatiites.

1.1 Etymology

The word “basalt” is ultimately derived from LateLatin basaltes, a misspelling of Latin basanites “veryhard stone”, which was imported from Ancient Greekβασανίτης (basanites), from βάσανος (basanos, “touch-stone”) and perhaps originated in Egyptian bauhun“slate”.[2] The modern petrological term basalt describ-ing a particular composition of lava-derived rock origi-nates from its use by Georgius Agricola in 1556 in hisfamous work of mining and mineralogy De re metallica,libri XII. Agricola applied “basalt” to the volcanic blackrock of the Schloßberg (local castle hill) at Stolpen, be-lieving it to be the same as the “very hard stone” described

1

2 2 OCCURRENCE

Columnar basalt at Szent György Hill, Hungary

Vesicular basalt at Sunset Crater, Arizona. US quarter for scale.

by Pliny the Elder in Naturalis Historiae.[3]

1.2 Types

• Tholeiitic basalt is relatively rich in silica and poor insodium. Included in this category are most basaltsof the ocean floor, most large oceanic islands, andcontinental flood basalts such as the Columbia RiverPlateau.

• Mid-ocean ridge basalt (MORB) is a tholeiiticbasalt commonly erupted only at ocean ridgesand is characteristically low in incompatibleelements.[4][5]

Large masses must cool slowly to form a polygonal joint pattern,as here at the Giant’s Causeway in Northern Ireland

Near Bazaltove, Ukraine

• High-alumina basalt may be silica-undersaturated or-oversaturated (see normative mineralogy). It hasgreater than 17% alumina (Al2O3) and is interme-diate in composition between tholeiite and alkalibasalt; the relatively alumina-rich composition isbased on rocks without phenocrysts of plagioclase.

• Alkali basalt is relatively poor in silica and rich insodium. It is silica-undersaturated and may containfeldspathoids, alkali feldspar and phlogopite.

• Boninite is a high-magnesium form of basalt that iserupted generally in back-arc basins, distinguishedby its low titanium content and trace-element com-position.

2 Occurrence

On Earth, most basalt magmas have formed bydecompression melting of the mantle. Basalt commonlyerupts on Io, the third largest moon of Jupiter, and hasalso formed on the Moon, Mars, Venus, and the asteroidVesta.

3.1 Geochemistry 3

The crustal portions of oceanic tectonic plates are com-posed predominantly of basalt, produced from upwellingmantle below, the ocean ridges.

3 Petrology

Photomicrograph of a volcanic (basaltic) sand grain; upper pic-ture is plane-polarized light, bottom picture is cross-polarizedlight, scale box at left-center is 0.25 millimeter. Note white pla-gioclase “microlites” in cross-polarized light picture, surroundedby very fine grained volcanic glass.

Themineralogy of basalt is characterized by a preponder-ance of calcic plagioclase feldspar and pyroxene. Olivinecan also be a significant constituent. Accessory mineralspresent in relatively minor amounts include iron oxidesand iron-titanium oxides, such as magnetite, ulvospinel,and ilmenite. Because of the presence of such oxide min-erals, basalt can acquire strong magnetic signatures as itcools, and paleomagnetic studies havemade extensive useof basalt.In tholeiitic basalt, pyroxene (augite and orthopyroxeneor pigeonite) and calcium-rich plagioclase are commonphenocryst minerals. Olivine may also be a phenocryst,and when present, may have rims of pigeonite. Thegroundmass contains interstitial quartz or tridymite orcristobalite. Olivine tholeiite has augite and orthopyrox-ene or pigeonite with abundant olivine, but olivine mayhave rims of pyroxene and is unlikely to be present inthe groundmass. Ocean floor basalts, erupted originallyat mid-ocean ocean ridges, are known as MORB (mid-ocean ridge basalt) and are characteristically low in in-

compatible elements.Alkali basalts typically have mineral assemblages thatlack orthopyroxene but contain olivine. Feldspar phe-nocrysts typically are labradorite to andesine in compo-sition. Augite is rich in titanium compared to augite intholeiitic basalt. Minerals such as alkali feldspar, leucite,nepheline, sodalite, phlogopite mica, and apatite may bepresent in the groundmass.Basalt has high liquidus and solidus temperatures—valuesat the Earth’s surface are near or above 1200 °C (liquidus)and near or below 1000 °C (solidus); these values arehigher than those of other common igneous rocks.The majority of tholeiites are formed at approximately50–100 km depth within the mantle. Many alkali basaltsmay be formed at greater depths, perhaps as deep as 150–200 km. The origin of high-alumina basalt continuesto be controversial, with disagreement over whether itis a primary melt or derived from other basalt types byfractionation.[6]:65

3.1 Geochemistry

Relative to most common igneous rocks, basalt composi-tions are rich in MgO and CaO and low in SiO2 and thealkali oxides, i.e., Na2O + K2O, consistent with the TASclassification.Basalt generally has a composition of 45–55 wt% SiO2,2–6 wt% total alkalis, 0.5–2.0 wt% TiO2, 5–14 wt% FeOand 14 wt% or more Al2O3. Contents of CaO are com-monly near 10wt%, those ofMgO commonly in the range5 to 12 wt%.High-alumina basalts have aluminium contents of 17–19wt% Al2O3; boninites have magnesium contents of upto 15 percent MgO. Rare feldspathoid-rich mafic rocks,akin to alkali basalts, may have Na2O + K2O contents of12% or more.The abundances of the lanthanide or rare-earth elements(REE) can be a useful diagnostic tool to help explain thehistory of mineral crystallisation as the melt cooled. Inparticular, the relative abundance of europium comparedto the other REE is often markedly higher or lower, andcalled the europium anomaly. It arises because Eu2+ cansubstitute for Ca2+ in plagioclase feldspar, unlike any ofthe other lanthanides, which tend to only form 3+ cations.Mid-ocean ridge basalts (MORB) and their intrusiveequivalents, gabbros, are the characteristic igneous rocksformed at mid-ocean ridges. They are tholeiites partic-ularly low in total alkalis and in incompatible trace el-ements, and they have relatively flat rare earth element(REE) patterns normalized to mantle or chondrite values.In contrast, alkali basalts have normalized patterns highlyenriched in the light REE, and with greater abundancesof the REE and of other incompatible elements. BecauseMORB basalt is considered a key to understanding plate

4 3 PETROLOGY

tectonics, its compositions have been much studied. Al-thoughMORB compositions are distinctive relative to av-erage compositions of basalts erupted in other environ-ments, they are not uniform. For instance, compositionschange with position along the Mid-Atlantic ridge, andthe compositions also define different ranges in differ-ent ocean basins.[7] Mid-ocean ridge basalts have beensubdivided into varieties such as normal (NMORB) andthose slightly more enriched in incompatible elements(EMORB).Isotope ratios of elements such as strontium, neodymium,lead, hafnium, and osmium in basalts have been muchstudied to learn about the evolution of the Earth’s man-tle. Isotopic ratios of noble gases, such as 3He/4He, arealso of great value: for instance, ratios for basalts rangefrom 6 to 10 for mid-ocean ridge tholeiite (normalized toatmospheric values), but to 15–24 and more for ocean-island basalts thought to be derived from mantle plumes.Source rocks for the partial melts probably include bothperidotite and pyroxenite (e.g., Sobolev et al., 2007).

3.2 Morphology and textures

An active basalt lava flow

The shape, structure and texture of a basalt is diagnosticof how and where it erupted—whether into the sea, in anexplosive cinder eruption or as creeping pahoehoe lavaflows, the classic image of Hawaiian basalt eruptions.

3.2.1 Subaerial eruptions

Main article: Subaerial eruption

Basalt that erupts under open air (that is, subaerially)forms three distinct types of lava or volcanic deposits:scoria; ash or cinder (breccia); and lava flows.Basalt in the tops of subaerial lava flows and cinder coneswill often be highly vesiculated, imparting a lightweight“frothy” texture to the rock. Basaltic cinders are oftenred, coloured by oxidized iron from weathered iron-richminerals such as pyroxene.

ʻAʻā types of blocky, cinder and breccia flows of thick,viscous basaltic lava are common in Hawaii. Pāhoehoeis a highly fluid, hot form of basalt which tends to formthin aprons ofmolten lava which fill up hollows and some-times forms lava lakes. Lava tubes are common featuresof pahoehoe eruptions.Basaltic tuff or pyroclastic rocks are rare but not un-known. Usually basalt is too hot and fluid to build up suf-ficient pressure to form explosive lava eruptions but occa-sionally this will happen by trapping of the lava within thevolcanic throat and buildup of volcanic gases. Hawaii’sMauna Loa volcano erupted in this way in the 19th cen-tury, as did Mount Tarawera, New Zealand in its violent1886 eruption. Maar volcanoes are typical of small basalttuffs, formed by explosive eruption of basalt through thecrust, forming an apron of mixed basalt and wall rockbreccia and a fan of basalt tuff further out from the vol-cano.Amygdaloidal structure is common in relict vesicles andbeautifully crystallized species of zeolites, quartz orcalcite are frequently found.

Columnar jointed basalt in Turkey

Columnar basalt See also: List of places withcolumnar basalt

During the cooling of a thick lava flow, contractionaljoints or fractures form. If a flow cools relatively rapidly,significant contraction forces build up. While a flowcan shrink in the vertical dimension without fracturing,it can't easily accommodate shrinking in the horizontaldirection unless cracks form; the extensive fracture net-work that develops results in the formation of columns.The topology of the lateral shapes of these columns canbroadly be classed as a random cellular network. Thesestructures are predominantly hexagonal in cross-section,but polygons with three to twelve or more sides can beobserved.[8] The size of the columns depends loosely onthe rate of cooling; very rapid cooling may result in verysmall (<1 cm diameter) columns, while slow cooling ismore likely to produce large columns.

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3.2.2 Submarine eruptions

Main article: Submarine eruption

Pillow basalts on the south Pacific seafloor

Outcrop of a pillow basalt, Italy

Pillow basalts Main article: Pillow lava

When basalt erupts underwater or flows into the sea, con-tact with the water quenches the surface and the lavaforms a distinctive pillow shape, through which the hotlava breaks to form another pillow. This “pillow” tex-ture is very common in underwater basaltic flows and isdiagnostic of an underwater eruption environment whenfound in ancient rocks. Pillows typically consist of a fine-grained core with a glassy crust and have radial jointing.The size of individual pillows varies from 10 cm up toseveral meters.When pahoehoe lava enters the sea it usually forms pil-low basalts. However, when a'a enters the ocean it formsa littoral cone, a small cone-shaped accumulation of tuffa-ceous debris formed when the blocky a'a lava enters thewater and explodes from built-up steam.

The island of Surtsey in the Atlantic Ocean is a basaltvolcano which breached the ocean surface in 1963. Theinitial phase of Surtsey’s eruption was highly explosive, asthe magma was quite wet, causing the rock to be blownapart by the boiling steam to form a tuff and cinder cone.This has subsequently moved to a typical pahoehoe-typebehaviour.Volcanic glass may be present, particularly as rinds onrapidly chilled surfaces of lava flows, and is commonly(but not exclusively) associated with underwater erup-tions.Pillow basalt is also produced by some subglacial volcaniceruptions.

4 Life on basaltic rocks

The common corrosion features of underwater volcanicbasalt suggest that microbial activity may play a sig-nificant role in the chemical exchange between basalticrocks and seawater. The significant amounts of reducediron, Fe(II), and manganese, Mn(II), present in basalticrocks provide potential energy sources for bacteria. SomeFe(II)-oxidizing bacteria cultured from iron-sulfide sur-faces are also able to grow with basaltic rock as asource of Fe(II).[9] Fe- and Mn- oxidizing bacteria havebeen cultured from weathered submarine basalts of LoihiSeamount.[10] The impact of bacteria on altering thechemical composition of basaltic glass (and thus, theoceanic crust) and seawater suggest that these interactionsmay lead to an application of hydrothermal vents to theorigin of life.

5 Distribution

Paraná Traps, Brazil

Basalt is one of the most common rock types in theworld. Basalt is the rock most typical of large igneousprovinces. The largest occurrences of basalt are in theocean floor that is almost completely made up by basalt.Above sea level basalt is common in hotspot islands and

6 7 ALTERATION OF BASALT

around volcanic arcs, specially those on thin crust. How-ever, the largest volumes of basalt on land correspondto continental flood basalts. Continental flood basaltsare known to exist in the Deccan Traps in India, theChilcotin Group in British Columbia, Canada, the ParanáTraps in Brazil, the Siberian Traps in Russia, the Karooflood basalt province in South Africa, the Columbia RiverPlateau of Washington and Oregon.Many archipelagoes and island nations have an over-whelming majority of its exposed bedrock made up bybasalt due to being above hotspots, for example, Icelandand Hawaii.Ancient Precambrian basalts are usually only found infold and thrust belts, and are often heavily metamor-phosed. These are known as greenstone belts, becauselow-grade metamorphism of basalt produces chlorite,actinolite, epidote and other green minerals.

6 Lunar and Martian basalt

Lunar olivine basalt collected by Apollo 15.

The dark areas visible on Earth’s moon, the lunar maria,are plains of flood basaltic lava flows. These rockswere sampled by the manned American Apollo program,the robotic Russian Luna program, and are representedamong the lunar meteorites.Lunar basalts differ from their terrestrial counterpartsprincipally in their high iron contents, which typicallyrange from about 17 to 22 wt% FeO. They also possess astunning range of titanium concentrations (present in themineral ilmenite), ranging from less than 1 wt% TiO2,to about 13 wt.%. Traditionally, lunar basalts have beenclassified according to their titanium content, with classesbeing named high-Ti, low-Ti, and very-low-Ti. Never-theless, global geochemical maps of titanium obtainedfrom the Clementine mission demonstrate that the lunarmaria possess a continuum of titanium concentrations,and that the highest concentrations are the least abundant.

Lunar basalts show exotic textures and mineralogy, par-ticularly shock metamorphism, lack of the oxidation typi-cal of terrestrial basalts, and a complete lack of hydration.While most of the Moon's basalts erupted between about3 and 3.5 billion years ago, the oldest samples are 4.2 bil-lion years old, and the youngest flows, based on the agedating method of crater counting, are estimated to haveerupted only 1.2 billion years ago.Basalt is also a common rock on the surface of Mars, asdetermined by data sent back from the planet’s surface,[11]and by Martian meteorites.

7 Alteration of basalt

7.1 Metamorphism

Basalt structures in Namibia

Basalts are important rocks within metamorphic belts,as they can provide vital information on the conditionsof metamorphism within the belt. Various metamorphicfacies are named after the mineral assemblages and rocktypes formed by subjecting basalts to the temperaturesand pressures of the metamorphic event. These are:

• Blueschist facies

• Eclogite facies

• Granulite facies

• Greenschist facies

• Zeolite facies

Metamorphosed basalts are important hosts for a vari-ety of hydrothermal ore deposits, including gold deposits,copper deposits, volcanogenic massive sulfide ore de-posits and others.

7.2 Weathering

Main article: Weathering

7

Compared to other rocks found on Earth’s surface, basaltsweather relatively fast. The typically iron-rich mineralsoxidise rapidly in water and air, staining the rock a brownto red colour due to iron oxide (rust). Chemical weath-ering also releases readily water-soluble cations such ascalcium, sodium and magnesium, which give basaltic ar-eas a strong buffer capacity against acidification. Calciumreleased by basalts binds up CO2 from the atmosphereforming CaCO3 acting thus as a CO2 trap. To this it mustbe added that the eruption of basalt itself is often associ-ated with the release of large quantities of CO2 into theatmosphere from volcanic gases.

8 Uses

Basalt is used in construction (e.g. as building blocks orin the groundwork), making cobblestones (from colum-nar basalt) and in making statues. Heating and extrudingbasalt yields stone wool, said to be an excellent thermalinsulator.Carbon sequestration in basalt has been studied as ameans of removing carbon dioxide, produced by hu-man industrialization, from the atmosphere. Underwaterbasalt deposits, scattered in seas around the globe, havethe added benefit of the water serving as a barrier to there-release of CO2 into the atmosphere.[12]

9 See also

• Basalt fiber

• Flood basalt

• Igneous rocks

• Mafic rocks

• Spilite

• Volcano

10 References[1] “basalt, n.”. Oxford English Dictionary Online. Oxford

University Press. September 2015. Retrieved 4 Novem-ber 2015.

[2] Harper, Douglas. “basalt (n.)". Online Etymology Dictio-nary. Retrieved 4 November 2015.

[3] Pliny the Elder, Naturalis Historiae. Book 36, section11 (Loeb Classical Library): “The Egyptians also discov-ered in Ethiopia what is called basanites, a stone which incolour and hardness resembles iron: hence the name theyhave given it.” This stone is now believed to have beengreywacke, a sedimentary rock unrelated to basalt.

[4] Hyndman, Donald W. (1985). Petrology of igneous andmetamorphic rocks (2nd ed.). McGraw-Hill. ISBN 0-07-031658-9.

[5] Blatt, Harvey and Robert Tracy (1996). Petrology (2nded.). Freeman. ISBN 0-7167-2438-3.

[6] Ozerov, Alexei Y (January 2000). “The evolution of high-alumina basalts of the Klyuchevskoy volcano, Kamchatka,Russia, based on microprobe analyses of mineral inclu-sions”. Journal of Volcanology and Geothermal Research95 (1-4): 65–79. doi:10.1016/S0377-0273(99)00118-3.

[7] Hofmann, A. W. (21 October 2014). “3.3 – SamplingMantle Heterogeneity through Oceanic Basalts: Isotopesand Trace Elements”. In Carlson, Richard W. The Man-tle and Core. Treatise on Geochemistry 3. Elsevier B.V.pp. 67–101. doi:10.1016/B978-0-08-095975-7.00203-5. ISBN 978-0-08-098300-4.

[8] Weaire, D.; Rivier, N. (20 August 2006). “Soap,cells and statistics—random patterns in two di-mensions”. Contemporary Physics 25 (1): 59–99.doi:10.1080/00107518408210979.

[9] Edwards, Katrina J.; Bach, Wolfgang; Rogers, Daniel R.(April 2003). “Geomicrobiology of the Ocean Crust: ARole for Chemoautotrophic Fe-Bacteria”. Biological Bul-letin 204: 180–185. Retrieved 4 November 2015.

[10] Templeton, Alexis S.; Staudigel, Hubert; Tebo,Bradley M. (April 2005). “Diverse Mn(II)-OxidizingBacteria Isolated from Submarine Basalts at LoihiSeamount”. Geomicrobiology Journal 22 (3-4): 127–139.doi:10.1080/01490450590945951.

[11] Grotzinger, J. P. (26 September 2013). “Analysis of Sur-face Materials by the Curiosity Mars Rover”. Science 341(6153): 1475–1475. doi:10.1126/science.1244258.

[12] Hance, Jeremy (5 January 2010). “Underwater rockscould be used for massive carbon storage on America’sEast Coast”. Mongabay. Retrieved 4 November 2015.

11 Further reading

• Alexander Ablesimov, N. E.; Zemtsov, A.N. (2010). Релаксационные эффекты внеравновесных конденсированных системах.Базальты: от извержения до волокна [Relax-ation effects in nonequilibrium condensed systems.Basalts from eruption to fiber] (in Russian).Moscow.

• Francis, Peter; Oppenheimer, Clive (2003). Volca-noes (2nd ed.). Oxford: Oxford University Press.ISBN 0-19-925469-9.

• Gill, Robin (2010). Igneous rocks and processes :a practical guide. Chichester, West Sussex, UK:Wiley-Blackwell. ISBN 978-1-4443-3065-6.

8 12 EXTERNAL LINKS

• Hall, Anthony (1996). Igneous petrology. Har-low: Longman Scientific & Technical. ISBN9780582230804.

• Alexander V. Sobolev, Albrecht W. Hofmann,Dmitry V. Kuzmin, GregoryM. Yaxley, Nicholas T.Arndt, Sun-Lin Chung, Leonid V. Danyushevsky,Tim Elliott, Frederick A. Frey, Michael O. Gar-cia, Andrey A. Gurenko, Vadim S. Kamenet-sky, Andrew C. Kerr, Nadezhda A. Krivolut-skaya, Vladimir V.Matvienkov, Igor K. Nikogosian,Alexander Rocholl, Ingvar A. Sigurdsson, NadezhdaM. Sushchevskaya, and Mengist Teklay (20 April2007). “The Amount of Recycled Crust in Sourcesof Mantle-Derived Melts”. Science 316 (5823):412–417.

• Siegesmund, Siegfried; Snethlage, Rolf, eds.(2013). Stone in architecture properties, durabil-ity (3rd ed.). Springer Science & Business Media.ISBN 3662100703.

• Young, Davis A. (2003). Mind over magma : thestory of igneous petrology. Princeton, N.J.: Prince-ton University Press. ISBN 0-691-10279-1.

12 External links• Basalt Columns

• Basalt in Northern Ireland

• Lava–water interface

• PetDB, the Petrological Database

• Petrology of Lunar Rocks and Mare Basalts

• Pillow lava USGS

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13 Text and image sources, contributors, and licenses

13.1 Text• Basalt Source: https://en.wikipedia.org/wiki/Basalt?oldid=695517288 Contributors: AxelBoldt, Magnus Manske, Mav, Bryan Derksen,

Zundark, Andre Engels, Ktsquare, Olivier, Spiff~enwiki, Lir, Brainsik, Michael Hardy, Ixfd64, Theanthrope, Ellywa, Darkwind, Glenn,Susurrus, Mxn, Hike395, Zimbres, Dino, Tempshill, Fvw, Flockmeal, David.Monniaux, Slawojarek, Skaffman, Moriori, Chris 73, Nurg,Modulatum, Hadal, Modeha, Decumanus, Leonard G., Gilgamesh~enwiki, Gracefool, Utcursch, Zeimusu, Antandrus, Beland, Phe,Bumm13, GeoGreg, Mozzerati, Karl-Henner, Atemperman, Mschlindwein, Avihu, Zeman, Fanghong~enwiki, Rich Farmbrough, Vsmith,Grutter, Kbh3rd, Jonathanischoice, Brian0918, Syp, El C, Kwamikagami, Peter Greenwell, Bobo192, Harald Hansen, Bontenbal, .:Ajvol:.,Jojit fb, Goldfinch~enwiki, Obradovic Goran, Sam Korn, HasharBot~enwiki, Siim, Alansohn, Jared81, CJ, Avenue, Snowolf, Gene Ny-gaard, Oleg Alexandrov, Ian Moody, Jeffrey O. Gustafson, Woohookitty, Jannex, RHaworth, Jdorje, LOL, Benbest, Sir Lewk, Kelisi,Eyreland, Fxer, Matilda, Ashmoo, Chun-hian, Sjakkalle, Kinu, Hathawayc, Williamborg, FlaBot, SchuminWeb, Latka, Gurch, Quux-plusone, Chobot, DVdm, Bgwhite, Gwernol, YurikBot, Hairy Dude, Hornandsoccer, Pigman, Ansell, Stephenb, CambridgeBayWeather,Shaddack, Member, Bovineone, RUL3R, Iancarter, Zwobot, JPMcGrath, Lockesdonkey, DeadEyeArrow, Bota47, Asarelah, Dan Austin,Wknight94, Lycaon, Wsiegmund, Anclation~enwiki, Mais oui!, Lagrima, Attilios, SmackBot, Unschool, McGeddon, DCDuring, Rokfaith,Blue520, Xaosflux, Macintosh User, Hmains, Mirokado, Biatch, Persian Poet Gal, MK8, Jnelson09, Droll, DHN-bot~enwiki, Sbharris,Can't sleep, clown will eat me, OrphanBot, Xiagu, Rolinator, Gump Stump, Ligulembot, Nmnogueira, ArglebargleIV, Erimus, Anlace,Soap, Kuru, Edetic, Zaphraud, Zslevi, LWF, JorisvS, IronGargoyle, RomanSpa, A. Parrot, Rickert, Clchen711, Geologyguy, Michael-busch, Lithium6ion, Tawkerbot2, Ouishoebean, Poolkris, Irwangatot, Dycedarg, Searles2sels, A Softer Answer, B, Chrislk02, Shers7,Jstuby, Casliber, Thijs!bot, Epbr123, IThink4u, Kablammo, Marek69, Astynax, Zachary, Dawnseeker2000, AntiVandalBot, Majorly, Ba-jan64, Gioto, Omphacite, Milesflint, CPMartin, Lordmetroid, Spencer, Rico402, Fireice, AubreyEllenShomo, Sluzzelin, Mikenorton, Vol-canoguy, D99figge, Deflective, WolfmanSF, Bongwarrior, VoABot II, Dentren, Professor marginalia, JNW, Kevinmon, Frotz, DerHexer,JaGa, MartinBot, Mschel, Bus stop, CommonsDelinker, WelshMatt, J.delanoy, Trusilver, Extransit, GeoWriter, J Dezman, Lunokhod,Eric Christiansen, Animaegurl, Bramblez, Chiswick Chap, DadaNeem, SJP, Biglovinb, Cometstyles, Treisijs, CardinalDan, Idioma-bot,VolkovBot, CWii, Johan1298~enwiki, Jeff G., Seattle Skier, Soliloquial, MissoulaMt, TXiKiBoT, Zamphuor, Eve Hall, Vipinhari, Qxz,Piperh, JhsBot, Gmichaelj, Synthebot, Peldbdi, Praefectorian, Chelydramat, EmxBot, D. Recorder, SieBot, Ivan Štambuk, BotMultichill,Phe-bot, Mbz1, Caltas, Matthew Yeager, Lucasbfrbot, Editore99, Youngbuck4 life, Tombomp, Mygerardromance, Finetooth, Sfan00 IMG,ClueBot, NickCT, Avenged Eightfold, Gits (Neo), Fyyer, The Thing That Should Not Be, Meekywiki, Der Golem, Cp111, I am a vio-linist, Awickert, Anonymous101, Jusdafax, Eeekster, Ric Metal Heart, SpikeToronto, NuclearWarfare, Jotterbot, Dekisugi, LadyEditor,Versus22, Jetsssicea, PCHS-NJROTC, Jjjss, Qfl247, Jk8894, Jbeans, Jamesrlforsyth, Addbot, Lordoliver, Denali134, Some jerk on the In-ternet, Fyrael, Ka Faraq Gatri, Jim10701, Proxima Centauri, AndersBot, Arteyu, Lightbot, ,ماني Gail, Middayexpress, Luckas-bot, Yobot,IW.HG, AnomieBOT, Jim1138, Galoubet, Citation bot, Bob Burkhardt, Johncatman, LilHelpa, Xqbot, Capricorn42, Δζ, Fountain Lake,Nel517, AbigailAbernathy, GrouchoBot, Adkjfkjdng, Frankie0607, RibotBOT, Franco3450, Eighthcreek, Shadowjams, WebCiteBOT,Samwb123, Imveracious, FrescoBot, Adam9389, Schnobby, BoundaryRider, OgreBot, Pinethicket, Katieni, Longview32, Jschnur, MKFI,Tobias1984, Theo10011, Frequenttraveller, Ncttrenc, DARTH SIDIOUS 2, Wikipauldia, Beyond My Ken, Born2bgratis, CalicoCatLover,Look2See1, GoingBatty, RA0808, Sunnybeach42301, Stormchaser89, Chiton magnificus, Ida Shaw, Rppeabody, BeetleBob, Aeonx, Eni-agrom, RockMagnetist, Peter Karlsen, TYelliot, Mikhail Ryazanov, ClueBot NG, BarrelProof, Armouredduck, Wbm1058, Lowercasesigmabot, BG19bot, Vagobot, ISTB351, Gorthian, Nightravin123, Snow Blizzard, Droit de Suite, Pseudofusulina, BattyBot, Zip34532,Ay10288, Бучач-Львів, Prokaryotes, Fremantle99, Sietecolores, Qwertyxp2000, RLTopp, Julietdeltalima, KasparBot, ManyMore andAnonymous: 364

13.2 Images• File:20011005-0039_DAS_large.jpg Source: https://upload.wikimedia.org/wikipedia/commons/7/7b/20011005-0039_DAS_large.jpgLicense: Public domain Contributors: United States Department of the Interior, United States Geological Survey, http://volcanoes.usgs.gov/images/pglossary/basalt.php Original artist: United States Geological Survey

• File:Basalt_columns_in_yellowstone_2.jpg Source: https://upload.wikimedia.org/wikipedia/commons/2/27/Basalt_columns_in_yellowstone_2.jpg License: CC BY-SA 3.0 Contributors: Own work Original artist: Brocken Inaglory

• File:Basalt_structures.jpg Source: https://upload.wikimedia.org/wikipedia/commons/a/a8/Basalt_structures.jpg License: CC BY-SA3.0 Contributors: Own work Original artist: Schnobby

• File:Boyabat.jpg Source: https://upload.wikimedia.org/wikipedia/commons/e/e7/Boyabat.jpg License: CC-BY-SA-3.0 Contributors:Transferred from en.wikipedia to Commons by BokicaK using CommonsHelper. Original artist: Lagrima at English Wikipedia

• File:Commons-logo.svg Source: https://upload.wikimedia.org/wikipedia/en/4/4a/Commons-logo.svg License: ? Contributors: ? Originalartist: ?

• File:Folder_Hexagonal_Icon.svg Source: https://upload.wikimedia.org/wikipedia/en/4/48/Folder_Hexagonal_Icon.svg License: Cc-by-sa-3.0 Contributors: ? Original artist: ?

• File:Giants_causeway_closeup.jpg Source: https://upload.wikimedia.org/wikipedia/commons/7/7f/Giants_causeway_closeup.jpg Li-cense: Public domain Contributors: Own work Original artist: Matthew Mayer (User Matthewmayer in English Wikipedia)

• File:ItalyPillowBasalt.jpg Source: https://upload.wikimedia.org/wikipedia/commons/7/79/ItalyPillowBasalt.jpg License: CC BY-SA3.0 Contributors: I (Qfl247 (talk)) created this work entirely by myself. (Original uploaded on en.wikipedia) Original artist: Qfl247 (talk)(Transfered by bramfab/Original uploaded by Qfl247)

• File:Lunar_Olivine_Basalt_15555_from_Apollo_15_in_National_Museum_of_Natural_History.jpg Source: https://upload.wikimedia.org/wikipedia/commons/2/29/Lunar_Olivine_Basalt_15555_from_Apollo_15_in_National_Museum_of_Natural_History.jpg License: CC BY-SA 3.0 Contributors: Own work Original artist: Wknight94 <a href='//commons.wikimedia.org/wiki/User_talk:Wknight94' title='User talk:Wknight94'>talk</a>

• File:LvMS-Lvm.jpg Source: https://upload.wikimedia.org/wikipedia/commons/5/5a/LvMS-Lvm.jpg License: CC BY-SA 3.0 Contribu-tors: I (Qfl247 (talk)) created this work entirely by myself. Original artist: Qfl247 (talk)

10 13 TEXT AND IMAGE SOURCES, CONTRIBUTORS, AND LICENSES

• File:Parana_traps.JPG Source: https://upload.wikimedia.org/wikipedia/commons/d/d4/Parana_traps.JPG License: CCBY-SA 2.5 Con-tributors: Own work Original artist: Eurico Zimbres

• File:People_icon.svg Source: https://upload.wikimedia.org/wikipedia/commons/3/37/People_icon.svg License: CC0 Contributors: Open-Clipart Original artist: OpenClipart

• File:Pillow_basalt_crop_l.jpg Source: https://upload.wikimedia.org/wikipedia/commons/0/08/Pillow_basalt_crop_l.jpg License: Publicdomain Contributors: Corrected version of Nur05018.jpg (taken from http://www.photolib.noaa.gov/htmls/nur05018.htm) Original artist:National Oceanic and Atmospheric Administration

• File:Portal-puzzle.svg Source: https://upload.wikimedia.org/wikipedia/en/f/fd/Portal-puzzle.svg License: Public domain Contributors: ?Original artist: ?

• File:Puu_Oo_cropped.jpg Source: https://upload.wikimedia.org/wikipedia/commons/6/6d/Puu_Oo_cropped.jpg License: Public do-main Contributors: USGS Original artist: G.E. Ulrich, USGS. Cropping by Hike395 (talk · contribs)

• File:Szentgyörgyhegy03.jpg Source: https://upload.wikimedia.org/wikipedia/commons/f/fe/Szentgy%C3%B6rgyhegy03.jpg License:Public domain Contributors: Own work Original artist: Darinko

• File:Text_document_with_red_question_mark.svg Source: https://upload.wikimedia.org/wikipedia/commons/a/a4/Text_document_with_red_question_mark.svg License: Public domain Contributors: Created by bdesham with Inkscape; based upon Text-x-generic.svgfrom the Tango project. Original artist: Benjamin D. Esham (bdesham)

• File:Translation_to_english_arrow.svg Source: https://upload.wikimedia.org/wikipedia/commons/8/8a/Translation_to_english_arrow.svg License: CC-BY-SA-3.0 Contributors: Transferred from en.wikipedia; transferred to Commons by User:Faigl.ladislav usingCommonsHelper.Original artist: tkgd2007. Original uploader was Tkgd2007 at en.wikipedia

• File:VessicularBasalt1.JPG Source: https://upload.wikimedia.org/wikipedia/commons/d/d6/VessicularBasalt1.JPG License: Public do-main Contributors: Transferred from en.wikipedia Original artist: Jstuby at en.wikipedia

• File:Wikisource-logo.svg Source: https://upload.wikimedia.org/wikipedia/commons/4/4c/Wikisource-logo.svg License: CC BY-SA 3.0Contributors: Rei-artur Original artist: Nicholas Moreau

• File:Базальтове.jpg Source: https://upload.wikimedia.org/wikipedia/commons/c/c5/%D0%91%D0%B0%D0%B7%D0%B0%D0%BB%D1%8C%D1%82%D0%BE%D0%B2%D0%B5.jpg License: GFDL Contributors: ? Original artist: ?

13.3 Content license• Creative Commons Attribution-Share Alike 3.0