Introduction

The study of ore deposits in the field is essential for the understanding of their formation.

Furthermore, the sharing of knowledge between students and professional geologists is particularly

important for both the education of future geologists, and also keeping professionals up to date with

recent scientific advancements in economic geology. With this in mind, our Chapter organised a 16-

day field trip to Eastern Europe, for both students and industry representatives, with the primary

aim of studying the relationships between porphyry and epithermal regimes in three different

mineral districts in Romania, Serbia and Bulgaria.

The western segment of the Tethyan Magmatic Arc, extending through Romania, Serbia and Bulgaria

is a world-class mining district hosting a wealth of large copper-gold ore deposits. Mining in the

region dates back over 4000 years, and has provided an important role in the history of European

civilisations right up until the present day. With recent political changes in Eastern Europe, the area

has experienced renewed interest in exploration and offers potential for a significant increase in

mineral production, particularly given a number of important recent discoveries.

The trip brought together 9 students in economic geology and 11 industry representatives. During

the 16 day trip we visited more than 14 deposits of a variety of different scales and stages of

development, focussed mainly on copper and gold systems. Mid-way through the trip, we also held a

symposium at the Technical Faculty in Bor, in collaboration with the University of Belgrade. The

symposium was a great success, bringing together economic geology students from the region, as

well as a number of industry representatives working in the Timok area.

Similar to the SEGF Student Field Courses, students were able to partake in the trip at a highly

reduced cost. To achieve this, we successfully raised more than £12,000 of funding, for which we

would like to thank industry participants and sponsor organisations below for their generous

donations. We also gratefully acknowledge the support of the numerous companies, for kindly

providing access to active operations, and to the mine staff who were exceptionally welcoming,

flexible and engaging.

Field Course Participants

Name

Affiliation

Hobbs, Tristan CRU Consulting

Garman, Jack First Quantum Minerals

Ireland, Timothy First Quantum Minerals

Tunningley, Andrew FWS Consultants

Kerr, Giles Independent

Herrington, Richard Natural History Museum

MacDonald, Francis Newmont Mining

Duffin, Adam Rio Tinto

Hawkes, Nick Rio Tinto

Walker, Sandy Rio Tinto

Gabiro, Michelle University of Brighton

Chant-Tuft, Olivia Imperial College London

Farmer, Nicholas Imperial College London

Fisher, Harry Imperial College London

Irwin, Matthew Imperial College London

Jeary, James Imperial College London

MacGowan, Stuart Imperial College London

Sievwright, Robert Imperial College London

Spencer, Edward Imperial College London

Dechev, Teo Mundoro Capital

Magaranov, Georgi Mundoro Capital

Map showing all projects visited and overnight stays during our field trip.

Group photo outside the entrance to the Catalina Monulesti gallery at Rosia Montana, Romania

Itinerary

DATE OVERNIGHT

Saturday, 4th July

Prior to 6:00PM: Participants arrive at Europa Royale Hotel, Bucharest 6:00PM: Trip briefing and icebreaker, followed by opening dinner Accommodation: Europa Royale Bucharest

Bucharest, Romania

Sunday, 5th July

9:00AM: Travel to Deva, Romania Accommodation: Hotel Sarmis

Deva, Romania

Monday, 6th July

9:00AM: Rosia Poieni Contact:Alexandra Scarlet (President of SEG chapter at University of Bucharest – alexa.scarlet@gmail.com) Accommodation: Hotel Sarmis

Deva, Romania

Tuesday, 7th July

10:00AM: Rosia Montana: Project presentation; Underground tour of Catalina Monulesti gallery; Tour of Cetate open-pit and Carnic areas; Core inspection Contact: Adrian Minut (Gabriel Resources) Accommodation: Hotel Sarmis

Deva, Romania

Wednesday, 8th July

9:00AM: Rovina Valley Project: Project presentation; Tour of Colnic deposit; Core review; Tour of Valea Morii open-pit Contact: Dr. Sorin Halga (Carpathian Gold) Accommodation: Hotel Sarmis

Deva, Romania

Thursday, 9th July

9:00AM: Certej Contact: Dr. Paul Ivascanu (Eldorado Gold) Accommodation: Hotel Sarmis

Deva, Romania

Friday, 10th July

9:00AM: Travel to Bor, Serbia Accommodation: Hotel Albo

Bor, Serbia

Saturday, 11th July

10:00AM: Majdanpek Contact: Sasa Stojadinovic – Assistant Professor at University of Belgrade Accommodation: Hotel Albo

Bor, Serbia

Sunday, 12th July

10:00AM: Veliki Krivelj Contact: Sasa Stojadinovic – Assistant Professor at University of Belgrade Accommodation: Hotel Albo

Bor, Serbia

Monday, 13th July

11:00AM: Cukaru Peki Contact: Dejan Kozelj (Freeport MacMoran) 2:00PM: International Students Conference (University of Belgrade): Poster session followed by a cocktail reception Contact: Sasa Stojadinovic - Assistant Professor at University of Belgrade Accommodation: Hotel Albo

Bor, Serbia

Tuesday, 14th July

9:30AM: Research Symposium: Student/Industry participant talks followed by a session on Timok Magmatic complex with local geologists Contact: Justin van der Toorn (Avala Resources) Sasa Stojadinovic - Assistant Professor at University of Belgrade

Accommodation: Hotel Albo

Bor, Serbia

Wednesday, 15th July

8:30AM: Field visits: A look at Reservoir Minerals’ and Avala Resources’ core-sheds in the morning, followed by numerous field visits in the afternoon Contact: Justin van der Toorn (Avala Resources) Dr. Tim Fletcher (Reservoir Minerals) Accommodation: Hotel Albo

Bor, Serbia

Thursday, 16th July

9:00AM: Travel to Sofia, Bulgaria Accommodation: Art Plaza Hotel

Sofia, Bulgaria

Friday, 17th July

10:00AM: Elatsite: Tour around Elatsite mine; Core inspection Contact: Vladislav Trashliev (Geotechmin) Guide: Kamen Bogdanov (Sofia University) Accommodation: Art Plaza Hotel

Sofia, Bulgaria

Saturday, 18th July

9:00AM: Chelopech: Project presentation; Core inspection; Vozdol gully visit Contact: Maria Doganova (Dundee Precious Metals) Accommodation: Hotel Ego

Plovdiv, Bulgaria

Sunday, 19th July

10:00AM: Ada Tepe: Project presentation; Tour of Ada Tepe Contact: Nikolay Zhivkov (Dundee Precious Metals) Accommodation: Hotel Yazovir Kardhzali

Kardzali, Bulgaria

Monday, 20th July

10:00AM: Madan: Visit to Crystal Hall museum; Visits to Petrovitsa and Kroushev Dol (operating deposits); Study of pre-ore rhyolite; Visit to specimen collectors 7:00PM: Closing dinner Contact/Guide: Dr. Rossitsa Vassileva (Bulgarian Academy of Sciences) Accommodation: Hotel Ego

Plovdiv, Bulgaria

Tuesday, 21st July

9:00AM: End of trip: Travel to Sofia for flight drop-off N/A

Figure: Map showing all projects visited and overnight stays during our field trip.

Part 1 – Romania

4-5th July – Arrival in Bucharest

All participants arrived in Bucharest on the afternoon of Sunday 5th July. Those who arrived

a little earlier in the day spent the day checking out a few of the sites of Bucharest, such as

the colossal Palace of the Parliament building. In the evening, we met up with 5 students

from the SEG Chapter at the

University of Bucharest, who

would be joining us for the

duration of the Romanian

part of the trip. After a trip

briefing held at the hotel, we

then headed out for some

traditional Romanian cuisine

under recommendation by

our Romanian friends for our

opening dinner. The next

day, we were picked up early

by Ovidiu, our cheerful driver

for the trip, and set off for

the Golden Quadrilateral.

6th July – Rosia Poieni

Our first mine visit was Rosia Poieni mine, the largest porphyry copper deposit in the

Apuseni Mountains, situated about 80km north of the city of Deva. Rosia Poieni lies

approximately 4km ENE of the Rosia Montana intermediate sulphidation Au-Ag deposit, and

is considered to be the porphyry system related to Rosia Montana. Copper production

began in 1983 and the mine is currently operated by the state company Cuprumin.

Trip briefing at the hotel at Bucharest delivered by Rob Sievwright, Vice-President of Imperial SEG

Admiring the view over the spectacular Rosia Poieni open pit

Jack leading a discussion of the geology at Rosia Poieni at the

end of our visit

We first visited the Head Office of Cuprumin in Abrud. Here we had a brief introductory

presentation to the deposit given by a director from Cuprumin, and received our access

passes to the mine – which had been kindly organised for us by Alexandra Scarlett,

president of the SEG Chapter at the University of Bucharest. We then proceeded to the

deposit, escorted by a mine engineer from Cuprumin.

The deposit is a classic porphyry

copper deposit, with mineralisation

related to the Middle Miocene

emplacement of a subvolcanic body,

the Fundoaia microdiorite, within the

andesitic host rocks. The deposit

exhibits a transition vertically from

porphyry Cu-Au mineralisation with

associated potassic alteration and

overprinting sericitic alteration, into

high-sulphidation at higher levels with

advanced argillic alteration zones.

Our visit to the site started with a look out over the open pit, where we observed the scale

of the active deposit. Here we also had a look a few examples of strong advanced argillic

alteration in the upper section of

the deposit. Our bus was then

escorted down into the base of the

open pit, where we could observe

some typical examples of

potassically altered porphyry

stockwork, with localised pyrite-

sericite alteration. Back out of the

pit, we finally observed examples of

propylitic alteration in the periphery

of the deposit and held a discussion

about what we had seen during our

visit which was led by Jack Garman,

a geologist from First Quantum

Minerals.

An example of porphyry vein stockwork at Rosia Poieni

Left: The various types of breccias are explained to the group in the Cetate open-pit

Right: Studying the mineralisation underground during our tour of the ancient Catalina Monulesti gallery

7th July – Rosia Montana

Rosia Montana is a low- to intermediate-sulphidation Au-Ag epithermal gold deposit

situated approximately 4 km WSW of Rosia Poieni, seen the previous day. Rosia Poieni is

considered to be the porphyry system related to Rosia Montana, so it made rather logical

sense to study Rosia Montana the consecutive day.

Rosia Montana is Europe’s largest gold deposit with an identified resource of 400 Mt @ 1.3

g/t Au and 6 g/t Ag. The deposit has a long history of gold production with mining dating

from as early as the first century AD. The deposit is hosted by a Maar-diatreme complex

consisting of a series of Miocene age breccias emplaced into Cretaceous flysch-type

sedimentary rocks and intruded by dacite domes. Mineralisation occurs predominantly

within the breccias, although some structurally controlled mineralisation is also found

within the cretaceous sediments beyond the boundary of the maar-diatreme complex.

Our visit to Rosia Montana began with a detailed introductory presentation on the deposit,

which clearly depicted the many types of breccias at Rosia Montana and their relationship

to mineralisation. We then set out on foot to the Cetate open-pit, where we were able to

hands on investigate the full sequence of breccia types. After lunch, we were were treated

to an underground tour of the Catalina Monulesti gallery, where we studied historic mining

workings dating as far back as Roman times. After the underground visit, we concluded the

day with a look through drill core of some representative sections. All in all, it was a

particularly well organised visit and a fascinating deposit.

Example of cross-cutting A- and B-veins in

drill core from the Colnic deposit

8th July – Rovina Valley Project

The Rovina Valley Project consists of three Au-Cu porphyry deposits – Rovina, Colnic and

Ciresata - which lie in close proximity along a linear N-S trend over approximately 8 km total

distance. The deposits are located approximately 10km E of Brad. Both Rovina and Colnic

are at surface, whereas Ciresata is blind at 50m below the surface. The total measured and

indicated resource of the deposit is 405.9 Mt @ 0.55 g/t Au and 0.14 % Cu for a total of 10.8

Moz Au. From north to south, there is a notable increase in the Au/Cu ratio sequence of

porphyry deposits, from the Rovina, Colnic and Ciresata deposits respectively. The

exceptionally high gold grades of the Ciresata porphyry make it unique to the Golden

Quadrilateral, and are comparable to the Au-rich porphyry deposits found in the Maricunga

belt in Chile.

Our day commenced with a particularly comprehensive presentation given by Dr. Sorin

Halga, the exploration manager at SAMAX. This covered all aspects of the project, from

historic mining in the region to set the scene, through to mine planning, but chiefly focussed

on the geology of the three deposits. This was

followed by a short field visit to a road cut, where

we saw hands-on examples of the early-mineral

porphyry and dacitic porphyry. Of particular

interest was the abundance of magnetite

alteration with euhedral hornblende phenocrysts

and late-stage hydrothermal magnetite stringers

which cross-cut the earlier mineralisation. After

the field stop, Sorin led us over to their core shed

where we got the chance to study representative

sections from each of the three porphyry

deposits, with local geologists on hand to go

through the most interesting parts. The drill

cores selected provided a good chance to see

some exceptional examples of cross-cutting A, B

and D veining. Finally, Sorin escorted us to the

abandoned Valea Morii open pit, a low-grade

porphyry Cu-Au deposit where we saw some

further examples of porphyry stockwork, cross-

cut by a later epithermal system. At both the

Rovina Valley porphyry deposits and Valea Morii,

the magnetite-chlorite-epidote alteration

assemblage in the stockwork was observed to be

strongly associated with the mineralisation.

After a fantastic day with SAMAX, we concluded the day

with a visit to the Brad Gold museum. The museum

exhibits an excellent suite of gold samples from all over

the world, although probably the most spectacular

specimens were those from the Golden Quadrilateral.

Some specimens of the collection were remarkably

spectacular, yet bizarre, such as the ‘golden lizard’ shown

right.

Visiting the abandoned Valea Morii open-pit

The ‘Golden Lizards’ at Brad

Gold Museum

Paul providing an introduction to the Certej deposit out

in the field with the open-pit in the background

9th July – Certej

Certej is an intermediate sulphidation epithermal gold deposit located 12 km north of Deva.

Gold mineralisation is hosted within Creteceous sedimentary rocks, which includes black

shales, siltstones and sandstones, as well as in Neogene conglomerates, volcanics and

intrusives.

On arrival, we were greeted by Dr. Paul

Ivascanu, and after a safety induction

got straight out into the field. Our first

stop was a look out over the current

open pit where Paul gave us a thorough

introduction to the deposit,

supplemented with a poster size cross

section and map of the deposit. This

was a fantastic way to get a grasp of the

deposit, providing a solid understanding

of the relationship between the three

intrusive phases, the Cretaceous and

Neogene sedimentary units, and

mineralisation.

Next stop, we studied the Dealu Grozii andesite just to the east of the deposit, one of the

intrusive phases, which although not responsible for bringing the mineralisation at Certej

hosts some mineralisation. The Dealu Grozii andesite contained mineralised veins known as

pebble dykes with large rounded clasts of quartz and a significant amount of disseminated

pyrite. Of particular interest in the pebble dykes were the two generations of sphalerite, one

honey coloured, and the other a darker red, as a result of formation at different

temperatures.

We then proceeded with our descent into the open pit by foot where we studied

Cretaceous sediments bearing mineralisation both disseminated and as veins and in voids

containing pyrite, arsenopyrite, galena and sphalerite. During our descent into the pit, Paul

encouraged discussion on topics such as the palaeo-tectonic setting of the deposit, which

was particularly helpful in enlightening our understanding of the Certej deposit.

After our field visit, we finished the day with a look at a number of representative drill holes,

accompanied by more stimulating discussion. Thanks Paul for a great day.

Left: Paul explaining the different lithologies at Certej with representative drill core examples.

Right: Dissolution breccia in Cretaceous black shale with several exotic fragments of the Baiaga Andesite, the central

intrusive phase which is considered to be responsible for bringing the mineralisation at Certej.

Part 2 – Serbia

11th July – Travel to Serbia

After an hour-long border crossing, and arriving in Serbia from Romania, the first thing to

note is the change in the quality of the road surface. This would become a topic of much

debate when we began to see the world-class deposits available. Our accommodation was

the Hotel Albo in the mining town of Bor, Northeast Serbia, two-hours drive from the

border.

On the evening of the 10th we met up with Justin van der Toorn, himself an RSM graduate,

who is the exploration manager for Avala Resources. For several months he had been in

correspondence with various operations in the vicinity of Bor to organise our visits. In

conjunction with Justin, our in-country guide was Sasa Stojadinovic, Assistant Professor at

the University of Belgrade Technical Faculty in Bor. Our time in Serbia would be comprised

of two sections; site visits and technical symposia. Site Visits took place over four days,

covering the Timok Magmatic Complex (TMC). The TMC is an elliptical belt of extrusive and

intrusive rocks, emplaced during the Cretaceous, and carbonate formations from

throughout the Mesozoic. The TMC makes up part of the larger ABCD metallogenic belt and

is the regional feature of the Bor District.

12th July - Majdanpek

Our first visit took us to the very North of the

TMC to the town of Majdanpek and the

producing porphyry copper mine which shares

the name. Owned and operated by RTB Group,

and known by the acronym RBM (Rudnik Bakra

Majdanpek, literally “Copper Mine Majdanpek”),

this is a high tonnage deposit with up to 0.8% Cu.

Before mining began, the orebody is thought to have had a tonnage of 1Gt, a true giant. The

deposit is composed of a series of narrow North-South trending fault-related andesite

dykes, which cut the Palaeozoic (and older) basement and Jurassic carbonates, forming a

contact aureole. The majority of mineralisation occurs as stockworks of veins adjacent to

intruding dykes, and is contained within the aureole. There are also multiple areas of skarn

mineralisation proximal to, and associated with, the intrusions. The average grade is around

0.6% copper with 0.3g/t Au with pyrite, chalcopyrite and magnetite the dominant

mineralogy in the stockwork, with accessory quartz, carbonate and sericite/chlorite

alteration. Our visit took in the South pit, which has largely ceased operation, from a

vantage point near its northern edge. Here the dykes and faults were seen to have the same

trend and complex stockworks of veins were visible. To both the East and West sides of the

pit are skarn deposits. Moving to the West side we examined the skarn up close, noting the

high extensive degree of alteration and iron content. We ended our visit with an

examination of some exemplary samples and core at the RBM office, where Professor

Richard Herrington realised he had produced some of these very samples many years

previously!

13th July – Veliki Krivelj and Bor

Appoximately 3km Northeast of the town of Bor lies the producing deposit of Veliki Krivelj, a

porphyry-copper body hosted in Upper Cretaceous hornblende andesite and its associated

pyroclastics. These pyroclastics have been interbedded with carbonate and pelitic units,

forming skarns with chalcopyrite disseminated throughout. Quartz diorite porphyry dykes

have intruded the andesite and overlying pyroclastics. Hydrothermal alteration is developed

dominantly in these pyroclastics where it results in biotitisation, calcititisation and

silicification. Locally, silicification is sufficiently weak as to allow chlorite and epidote to

develop. Ore mineralisation occurs late and overprints the andesite, dyke swarm and skarns,

forming a sub-rounded ore zone 1.5km long by 0.7km wide, with hydrothermal alteration at

its periphery. Chalcopyrite is the dominant ore mineral, though cubanite, bornite, chalcocite

and covellite occur locally as temperature and chemistry varies across the body. The ore

body is proven to a depth of over 800m producing a reserve of 2.5Mt at an average of 0.44%

copper. Our visit here comprised of a bus ride into the pit, stopping three times. The first

stop was in order to appreciate the magnitude of the operation, which had removed over

Richard Herrington and students overlooking the Southern Pit at Majdanpek

300m of the orebody as well as the top cover. Assistant Professor Sasa Stojadinovic gave an

in-depth explanation of the geology, having had much experience working at this site. Our

second and third stops were to examine the lithologies involved and the increase in grade

with depth, respectively.

After visiting Veliki Krivelj, we stopped off for a look out over the Bor open-pit. Formally

Rudnici Bakra Bor (RBB), this high-sulphidation epithermal deposit was related to a deeper

porphyry-style deposit, known as Borska Reka. Though the Bor deposit is no longer

extracted, work continues underground. Dominated by chalcocite and covellite this

epithermal regime produced grades of over 3% copper (up to 6%) and up to 3.75g/t Au. RTB

is currently in the process of backfilling the old pit. This is a colossal task which is evidenced

by the fact that the waste from Bor was once piled into the highest single-slope heap in the

world!

Bor open-pit from the look-out with the smelter in the background

Drill-rig in operation behind the Rakita Freeport-MacMoran premises and core-shed

14th July – Cukaru Peki and 2nd International Students Conference

The Cukaru Peki deposit is one of the most exciting exploration sites anywhere in the world.

This body exhibits various levels or zones which progressively change from a high-

sulphidation epithermal regime to porphyry-style mineralisation. In addition to this the

grades recorded by initial and follow-up drilling are astounding; intercepts of over 7%

copper equivalent are common. The epithermal, upper, zone consists of massive sulphide

ores of covellite, bornite, enargite and chalcocite. These are hosted in strongly altered

andesite which shows argillic overprinting. At depth, porphyry-style mineralisation is

composed of chalcopyrite-pyrite veins and blebs with rare molybdenite. Often the porphyry

zones exhibit argillic overprinting and associated later covellite mineralisation. Our visit

began with a brief safety talk followed by an excellent company presentation on the

regional and economic geology. Having not yet broken ground, we instead examined a

gigantic length of core, over 500m, exhibited at the Freeport-McMoran core shed, though

the project is a joint venture between Freeport-McMoran and Reservoir Minerals. The grade

was easy to see as the deep blue of covellite and bornite stood out even in the dully lit

hangar.

On the afternoon of the 13th July, the University of Belgrade Technical Faculty in Bor hosted

the 2nd International Students Conference bringing together students involved in the

mining sector and its associated industries from several countries. Students presented their

research posters on topics covering petrology, exploration, processing, mine engineering

and economics of mine planning. The day offered a fantastic opportunity for our chapter to

Left: Poster presenters from our group at the 2nd

International Students Conference

Right: Group photo with conference participants outside the Technical Faculty at Bor

Dr. Ed Spencer from the RSM presenting his research on El

Teniente at the Research Symposium

interact with student in economic geology from other countries, as well as a chance to

present some of our research.

14th July – Research Symposium and Short-course on Timok Magmatic Complex

The following day was devoted to a Research Symposium and Short-course, which drew

students and professionals from across Europe. The senior students of the Imperial College

SEG Chapter and industry professionals travelling with us presented their research from

dissertations and theses. The day was well received by all. As a show of thanks to individuals

who had aided us immeasurably in

the Serbian segment of the trip, the

Chapter gave out small gifts of

tankards emblazoned with the

crests of the Technical Faculty in Bor

and the Royal School of Mines.

These were awarded to Dr. Ljubisa

Balanovic, the President of the

conference Organising Committee,

and to the aforementioned Sasa

Stojadinovic and Justin van der

Toorn.

Program for the Research Symposium and Short-course on Timok Magmatic Complex

Studying drill core at Reservoir Mineral’s core-shed

15th July – Timok site visits with Avala Resources and Reservoir Minerals

Our last day in Serbia was devoted

to a tour of various localities within

the TMC. These were conducted

jointly by Avala Resources and

Reservoir Minerals. The morning

was spent first having a look at

several representative drill-cores at

both Reservoir and Avala Resources

core-sheds, followed by a tour

around the SGS labs, where we got

to see the whole assaying process

from drill-core to pulp.

In the afternoon, we split into groups to travel in 4x4s (our minibus would not be capable of

doing the off-roading involved). The first stop was at a small weakly mineralised porphyry

target called Red River. This is currently still being mapped with only surface exploration

having been conducted. Secondly we visited Copu Kupjatra, a highly silicified cap, composed

almost exclusively of vuggy silica and alunite, proving almost impossible to sample with

hammers. Persistence had produced samples which yielded 3-4 ppm of gold. Thirdly we saw

a disused open pit at Lipa. This had been an enargite-rich body and was mined in the 1950s.

Now it is completely flooded with typical acid-mine drainage water which will hinder any

attempts to re-open or –process the site. Excellent euhedral specimens of enargite, up to

50mm in size, were found at nearby tips. The final locality was a small porphyry, just

cropping out at the surface. This was heavily weathered though Justin van der Toorn

pointed out it was still possible to pick out altered veins which looked identical to tree roots.

Once we had our eye in, the stockwork became obvious. Once again, limited exploration of

this has been conducted.

With some time left at the end of the day, we were able to visit a

joint venture RC drill site run by First Quantum Minerals and

Mundoro. Many of the students had not yet seen a greenfield

exploration site so this was an excellent opportunity. Even more so

was a demonstration of the temperamental nature of machinery as,

having retrieved around 50m or so, the final rod would not release

the drill bit. The entire day was an outstanding view of what new

exploration is going on in the local TMC and, more generally, what we

can expect from working on such projects. We ended the day back at

Avala Resources’ office where they had very kindly laid out one of the

largest barbeques I’d ever seen. RC drill site we visited

Safety conscious students observe a haul trucks offloading into the gyratory crusher

Part 3 – Bulgaria

16th July – Travel to Bulgaria

Thursday was spent travelling from Bor in Serbia to Sofia, Bulgaria. Once in Sofia, we were

met by Kamen Bogdanov, an associate professor from the University of Sofia, who would be

our guide for Bulgaria. We were joined by students from the SEG chapter at the University

of Sofia and taken to their favourite restaurant.

17th July - Elatsite

Elatsite is an Upper Cretaceous Cu, Au porphyry deposit hosted in Palaeozoic granodiorites,

monzodiorites and phyllites. It is located 6km W of the High Sulphidation deposit of

Chelopech. It is a vein and disseminated type stockwork. Classic alteration assemblage of

potassic ore that grades to propyillitic with minor phyllic overprinting observed. The age of

mineralisation is 92.1+-0.3Ma. Ore minerals include bornite, chalcopyrite, pyrite and

molybdenite. Gold is hosted in inclusions in the chalcopyrite. Total measured resources are

185mT @ 0.4% Cu and 0.3 g/t Au.

En route to the mine we stopped at a field outcrop. The outcrop was a Palaeozoic

granodiorite with mafic enclaves suggesting magma mixing occurred. The granodiorite is the

host rock in which the porphyries are intruded. Upon arrival at the mine site and following

safety inductions a presentation was given by Kamen. This gave an introduction to the

mineral deposits in Bulgaria aswell as the system at Elatsite. We were then shown around

stock waste piles and identified classic phyllic and potassic alteration in hand specimen. An

exciting tour of the crushing plant concluded the pit visit.

We then viewed representative core alongside students working at the mine from the

University of Sofia who explained to us the cross cutting relationship of the granodiorte and

the monzodiorite porphyhs. To conclude the party was then shown into the main office to

see the modelling software used to create pit plans.

18th July Chelopech

Chelopech is a High Sulphidation Epithermal Au-Cu deposit.

Mineralisation occurs as steeply dipping massive sulphide

bodies with veinlets, veins and disseminated style. The age os

mineralisation is 91.45+-0.15Ma. Main ore minerals are:

pyrite, chalcopyrite, enargite, luzonite, tennantite, bornite

and galena/sphalerite. The deposit is hosted in advanced

argillic and intense silicified andesites and tuffs.

The visit to the mine started with a video safety tour and a goody bag presented to each

party member. We were shown into the core shed and inspected core from the mine. The

core displayed a host arsenosulphides which had not been seen at other deposits. The core

also displayed free gold, much to everyone’s excitement!

Free gold!!

Head mine office with a demonstration of the pit modelling software

Gully outcrop tour with

geologists giving an

overview of local

geology

Dundee precious metals own a specially designed smelter in Namibia able to process arsenic

rich concentrate which allows them to extract in Chelopech. The mine has two declines and

operates a sublevel longhole stoping technique. Unfortunately, we could not visit

underground. We were then taken off the mine site for a field visit up a gully to view an

uplifted barren porphyhy. It is interpreted that it is the precursor to the epithermal system

at Chelopech. Along the gully quartz sericite and pyrite alteration was prevalent. The system

at Chelopech and Elatsite are interpreted to not be related due to distance (>8km) and the

timing of mineralisation does not fit.

19th July - Ada Tepe

Ada Tepe is an advanced stage Au, Ag sedimentary hosted Low Sulphidation development

project. It has resources of 6.15Mt @ 4.6g/t Au, and has an open pit planned, with

construction work commencing in 2016. The deposit has a strong structural control with the

Tokachka detatchment fault acting as a conduit for fluids. The fault separates Palaeozoic

metamorphics and the Palaeocene sedimentary formation. Mineralisation is concentrated

on the fault and in the hanging wall sediments of the normal fault, and is aged at 34.99Ma.

Ore minerals are electrum, pyrite and trace galena, and gold silver telurides. Alteration is

dominated by quartz and adularia, with minor calcite, pyrite and dolomite.

The day started with a comprehensive presentation in a disused shoe factory from a

Bulgarian geologist and translated by a young English speaking geologist! The presentation

gave an overview of the development of the project and the geology. The talk was followed

by a drive up to the Ada Tepe site to view the famed ‘wall’ which marks the detachment

surface.

Left: Free gold being cross cut by micro normal faults in a quartz adularia assemblage.

Right: ‘The wall’ depicting the Tokachka detachment

We were also shown the ancient workings where Au had been extracted in the heavily

silicified rocks. The day finished with a look at some representative core samples that

showed the typical low sulphidation vuggy quartz. Free gold was also seen in the core!

20th July – Madan

Madan is a Pb-Zn-ag hydrothermal skarn deposit. The deposit has >95Mt @2.54%Pb and

2.1% Zn across 40 small mines. The mineralisation is hosted in continuous (2m x 7km) veins

and disseminated stockworks. There is a strong structural control with mineralisation

occurring in six subparallel NNW striking faults. Main ore minerals comprise galena,

sphalerite, chalcopyrite, pyrite. The mineralisation is hosted in gneisses, amphibolites and

schists, altered with quartz-sericite-pyrite and chlorite epidote alteration in silicic rocks and

rhodochrosite manganoan calcite in skarns.

The group was met by Rosita Vassileva the local expert on the Madan mining region. Rosita

accompanied the group to the local sample museum where there were spectacular galena

and sphalerite displays.

Left: The crystal hall museum in Madan

Right: The decline to the Petrovitsa mine at Madan

We then were taken on a outcrop tour of some of the mines in the region. The first locality

displayed classic skarn mineralisation and had large acicular hedenbergite crystals

intergrown with galena, sphalerite and chalcopyrtite.

The second locality was a waste ore pile where we were set loose to gather base metal

sulphide samples. The third locality was a roadside outcrop of a rhyolite, it is the only

magmatic infestation in the area. However it is proven to be unrelated through its age. The

group observed a crude ore transport system where rock is moved in cable cars several

kilometres up the valley to be processed. The day was concluded with a visit to a mineral

collector, to see his stash. Some of the trip bought lots of samples and struggled to get them

all home on the flight!

Left: Hiking to see the rhyolite with ore transport system in the background

Right: The mineral collector with his samples for sale