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SOFIA UNIVERSITY SEG STUDENT CHAPTER
FACULTY OF GEOLOGY AND GEOGRAPHY
15 Tsar Osvoboditel Blvd. 1504Sofia, Bulgaria
Mineral deposits of Czech Republic
Sofia SEG Student Chapter 2017 field trip
Field Trip Guidebook
Editors: Prof. K. Bogdanov, G. Markov, Z. Nanov
Sponsored by:
2
Sofia, Bulgaria
September, 2017
Contents
1.Introduction ....................................................................................................................................... 3
2.Geological outline ............................................................................................................................. 4
3.Geodynamics of the Bohemian Massif in Czech Republic ............................................................... 6
4.Mokrsko Au deposit (Psi hory gold district) - day 1 ....................................................................... 10
6.Krásná Hora - Milešov ore district - day 2 ...................................................................................... 13
7.Jilove Au deposit - day 3 ................................................................................................................. 14
8.Cinovec-Zinnwald Sn deposit - day 4 ............................................................................................. 15
9.The Krupka mining region - day 5 .................................................................................................. 16
References .............................................................................................................................................. 17
This guidebook is based on the Maserik Brno SEG Student Chapter guidebooks:
“Gold deposits in the Bohemian Massif, 2014” edited by: Vojtech Wertich, Jakub Vyaravski and Sven
Honig and “Mineral deposits of the Krusne hory, 2016” edited by: Vojtech Wertich and Jakub
Vyaravski with amendments.
3
1. Introduction
This guide book is designed to contribute understanding of the main geolgical characteristics of Czech
republic along with summary of the deposits and prospects that will be visited during the trip. It will be
held in the period 23-30th of September. The planned deposits for visit are: Mokrsko, Roudny, Krasna
hora, Jilove, Zinnwald, Krupka (Fig. 1). The idea behind this trip is to create a relationship between us
and the industry. The trip will be shared with our colleagues from Romania and Serbia.
Fig. 1 Map with the intended deposits to visit.
4
2. Geological outline
The Czech Republic is located in the very centre of Europe at the limit between the Hercynian Meso-
Europe and the Neo-Europe (Fig. 2). There is hardly any country with such a variegated geological
structure in such a small area and with such a complex geological evolution. Practically all known rocks
and the majority of geological formations and known types of ores and industrial minerals occur on the
state territory. Even though most ore deposits are interesting mainly from a scientific and mineral
collectors’ point of view, a number were of European importance during the Middle Ages and the
beginning of modern time. The interesting and complex history of this area attracted attention of
researchers already in early times and it strongly influenced the evolution of the mining and geological
sciences. It was on this territory where one of the oldest mining laws, the Jihlava Mining Law (1260),
and slightly later the mining law of the King Wenceslas II “Ius regale montanorum” (1300), which
became basis of many mining laws in other states of the world especially in South America, came into
being.
Three main structural complexes form the geological structure of Czech territory. The oldest
one, consolidated already during the Precambrian orogenies, is Brunia (Brunovistulicum), taking
basically the area of Moravia. This segment of the Earth’s crust probably represents an extremity of the
East European platform, even though some researchers consider it as a part of the African plate. The
influence of the younger – Paleozoic and Alpine – orogenies was only minor and it served as a foreland
of the nappe structures which were thrust over it. The Hercynian-consolidated Bohemian Massif,
overlapping to the area of the neighbouring Austria, Germany and Poland in the south, west and north,
Fig.2 Geological position of the Czech
Republic in Europe.
5
forms the major part of the state territory. Bohemian Massif belongs to the Paleo-Europe. The Hercynian
orogeny in the end of the Carboniferous put the finishing touches on it, even though it also contains older
building elements. It already behaved as a consolidated block after the Hercynian orogeny, only
sometimes flooded by epi-continental sea and affected only by fault tectonics. As a crustal block rising
from young sedimentary formations, it broke up only during the younger mountain-building processes,
morphologically only in the end of the Neogene and in the Quaternary. Geological continuation of the
Hercynides towards the west is indicated by other crustal blocks which were created later –
Schwarzwald, Vosges Mountains, the French Massif Central and Iberian Meseta, in the northern branch
then the Armorican Massif and massifs in southern England and Ireland. The eastern margin of the
Bohemian Massif was thrust over the Cadomian unit of the Brunovistulicum during the Hercynian
orogeny. The boundary between the hercynian Mesoeurope and alpine Neoeurope crosses the eastern
part of the Czech Republic. The Alpides are represented there by the West Carpathians.
They are built by an inner unit – Central West Carpathians, Outer Flysh Carpathians and the
Carpathian Foredeep. The Central West Carpathians are formed by pre-Mesozoic volcanosedimentary
complexes, mostly metamorphosed and penetrated by late-Hercynian granitoid plutons, and their
sedimentary cover (Trias to Lower Cretaceous). At the beginning of Upper Cretaceous the Central
Carpathians were intensively folded and in places also metamorphosed. A tectonic zone of first order –
the Klippen Belt, built mostly by Mesozoic sedimentary rocks separates the Central Carpathians from
the external Flysh Carpathians. The Outer Flysh Carpathians are formed (besides rare uppermost Jurassic
sediments and local Cretaceous volcanics) predominantly by sedimentary complexes of Cretaceous and
Paleogene age. These complexes were as horizontal nappes thrust over the Brunovistulian basement and
its sedimentary cover over a distance of tens of kilometres partly even over the Neogene Carpathian
Foredeep.
As in the study of the history of mankind, there is little information on the oldest periods of the
evolution of the Earth we live on, and our findings are accompanied by a large number of uncertainties.
This of course applies also for the Czech territory, even though it belongs to the areas where systematic
geological research was in progress since the beginning of the 19th century.
Complexes of the Brunia (Brunovistulicum) crop out on the surface only in the western
Moravia, but they reach far to the east below the overthrust nappes of the Outer Flysh Carpathians. They
are formed by metamorphic rocks – mainly monotonous biotite paragneisses – which were altered during
the Proterozoic orogenies, and intruded by huge massifs of abyssal magmatic rocks of about 550 Ma age
at the boundary between the Proterozoic and Paleozoic. The Brno and Dyje Massifs represent the
exposures of these rocks. Granitoid plutons covering large areas as well as smaller basic massifs of
gabbros and norites compacted this unit and prevented its later reworking by younger mountain-building
processes, which formed the Bohemian Massif. Western parts of the Brunovistulicum are built by
variegated volcano-sedimentary complexes (involving limestones, graphitic rocks, quartzites,
amphibolites and orthogneisses). These parts were strongly affected by the Hercynian
tectonometamorphic processes. They crop out from beneath of the overthrust Hercynian complexes of
the Moldanubicum and Lugicum in tectonic windows of the Dyje and Svratka Domes of the Moravicum
and Desná Dome of the Silesicum. Their appurtenance to the Brunia (Brunovistulicum) has not been
commonly accepted yet and these units are by some authors ranked to the Lower Paleozoic and to the
Hercynian Bohemian Massif. Platform sediments – the Cambrian conglomerates and sandstones in
limited areas, marine Silurian shales sporadically and extensive and important sediments of the
Devonian, Mississippian (Lower Carboniferous) and continental sediments of the coal-bearing
Pennsylvanian (Upper Carboniferous) – are deposited on the Cadomian basement. The younger platform
cover is represented by sediments of the Jurassic, Cretaceous, Paleogene and the Neogene of the
Carpathian Foredeep. This consolidated basement was overthrust by nappes of the Outer Flysh
Carpathians from the east (Fig. 3).
The lower level (basement) of the Bohemian Massif – the epi-Variscan platform – is built by
metamorphic rocks intruded by numerous and very large granitoids massifs, and by only weakly
6
metamorphosed or unmetamorphosed but Hercynian-folded Lower Paleozoic. Regionally it is divided
into the core, formed by the highly metamorphosed Moldanubicum and mostly only weakly
metamorphosed Bohemicum (Teplá-Barrandian domain). This core is rimmed by the Saxothuringicum
(Krušné hory Mts.) on the NW, Lugicum (Krkonoše Mts., Orlické hory Mts., Králický Snìžník) on the
north and Moravo-Silesicum (Jeseníky Mts., eastern part of the Èeskomoravská vrchovina Highlands)
on the east. These marginal complexes are metamorphosed mostly less intensively than the central
Moldanubicum.
Fig.3 Geology of the Czech Republic
3. Geodynamics of the Bohemian Massif in Czech Republic
The Bohemian Massif represents one of the largest exposure of the European Variscan belt located at its
eastern extremity (Fig. 4). The Variscan architecture of the Bohemian Massif can be defined by four
major tectonic units: 1) The Saxothuringian Neoproterozoic continental basement with its Palaeozoic
cover, 2) The Teplá-Barrandian (Bohemicum) Neoproterozoic basement and its Early Palaeozoic cover
of the Prague Basin (the Bohemia Terrane of South Armorica), 3) The Moldanubian high- to medium-
grade metamorphic unit intruded by numerous Carboniferous granitic plutons, altogether forming the
high-grade core of the orogen, 4) The easterly Brunia Neo-Proterozoic basement with Early to Late
Palaeozoic cover.
The Gondwana faunas of Lower Palaeozoic (Cambrian and Ordovician) sediments of the
Saxothuringian and Teplá-Barrandian domains and numerous isotopic and U-Pb zircon data imply
affinity to northern Gondwana margin. Schulmann et al. (2009) suggested that the Variscan structure of
the Bohemian Massif resulted from Andean type convergence and formed as a typical upper plate orogen
located above a long lasting Devonian-Carboniferous subduction system. These authors shown that all
the current criteria defining an Andean type of convergent margin are present and surprisingly well
7
preserved. In particular it is: 1) the development of blueschist facies metamorphism along the
Saxothuringian margin, 2) calc-alkaline to potassium rich (shoshonitic) arc type magmatism in distance
150 – 200 km from the suture zone (Žák et al., 2005), 3) back-arc basin developed on continental upper
plate crust later replaced by thick continental root (Schulmann et al., 2005), 4) deep granulite facies
metamorphism associated with supposed underplating of the crust by mafic magmas at the bottom of
the root and 5) continental lithosphere underthrust underneath the thickened root system. Based on these
criteria, the architecture of the eastern Variscan belt is interpreted as the result of a large-scale and long-
lasting subduction process associated with crustal tectonics, metamorphism, magmatic and sedimentary
additions that developed over the width of at least 500 km, in present coordinates, and time scale of ~80
Ma.
Neoproterozoic par-autochthon (Saxothuringian) is represented by migmatites and
paragneisses dated at ~580–550 Ma. These rocks are intruded by Cambro-Ordovician calc-alkaline
porphyritic granodiorites converted to augen orthogneiss during the Variscan orogeny. The basement is
unconformably covered by Cambrian and Ordovician sequences overlain by Late Ordovician to
Famennian pelagic sediments and Famennian to Visean flysh. The par-autochthon is thrust by
allochthonous units containing deep water equivalents of the Ordovician to Devonian rocks of the para-
autochthon and proximal flysh sediments.
Fig.4 Plate teconic map of the Bohemian Massif
8
The allochthonous consist of by pile of thrust sheets marked by decreasing pressure and
metamorphic age from the top to the bottom (Franke, 2000; Konopásek and Schulmann, 2005). In the
highest structural position occur thrust sheets with metabasites of Ordovician protolith age eclogitized
during Devonian (~395 Ma). Structurally deeper occur sheets associated with middle pressure
assemblages and Late Devonian zircon and Hbl cooling ages (~365 Ma). This rock pile represents Late
Ordovician to Devonian passive margin imbricated during Devonian convergence. In the Sudetic part of
the Bohemian Massif, the Ordovician rift sequences are characterized by the presence of deep marine
sediments and MORB type volcanics followed by Silurian and Devonian sedimentary sequences. The
Ordovician oceanic rocks are metamorphosed at blueschist-facies conditions probably at Late Devonian.
Metamorphic zones and facies: Ky – kyanite zone, St – staurolite zone, amphibolite facies, Grt
– granulite facie, Bt – blueschist facies
The oceanic subduction stage was followed by Carboniferous continental subduction of the
Saxothuringian continental rocks underneath easterly Teplá-Barrandian block which was responsible for
the eclogitization of continental crust at ~350–340 Ma (Schmädicke et al., 1995). This event is
responsible for the global reworking of the Saxothuringian at high pressure conditions, thrusting of
subducted continental crust and exhumation of deep rocks. The plutonic bodies contain numerous
xenoliths, screens of the Barrandian-like Palaeozoic and Neo-Proterozoic rocks.The Central Bohemian
Plutonic Complex is interpreted as a relatively shallow section (< 10 km) through the Devonian-
Carboniferous magmatic arc, which widened and expanded to the east with time. The Moldanubian
metamorphic units are commonly intruded by numerous Variscan plutons including magnesio-potassic
syenites to melagranites (durbachites), and S-type granitoids. The magnesio-potassic syenites to
melagranites are spatially, structurally and temporally associated with high-pressure granulites
(Janoušek and Holub, 2007). These rocks have isotopic signatures indicating a metasomatized
lithospheric mantle source, presumably contaminated by subducted mature crustal material. The
succession of tectonic events (Fig. 4) can be interpreted in terms of south-eastward (in the present-day
coordinates) oceanic subduction of large Saxohuringian ocean underneath an active continental margin,
obduction of the passive margin units, formation of a fore-arc region, growth of a magmatic arc and
development of a large-scale back-arc system on the continental lithosphere. The early Saxothuringian
oceanic subduction event was followed by a continental underthrusting of Saxothuringian continent
leading to gradual flattening of the subduction zone marked by eastward migration of arc depocenters
and subsequent crustal thickening. The latter event was responsible for the development of a thick
continental root at the expense of the upper plate composed of the Teplá-Barrandian and Moldanubian
units. The final evolution is marked by the continental indentation of easterly Brunia continent,
exhumation of the Moldanubian lower crust, collapse of the Teplá-Barrandian and Moldanubian
thrusting over Brunia platform.
Early Devonian oceanic subduction underneath the continental margin (Fig. 5) is marked by
relics of Ordovician to Lower Devonian passive margin metamorphosed under blueschist–eclogite facies
conditions indicating a Mid-Devonian oceanic subduction. These units are obducted above a
continuously underthrust continental Saxothuringian plate. The Barrovian metamorphic zonation and
related deformation in the overriding Teplá-Barrandian continental margin are interpreted as ductile part
of the Barrandian crust extruded during early stage of upper plate Late Devonian shortening. The steep
folding of central part of anchimetamorphic Barrandian Neoproterozoic sequences is interpreted as a
same deformation event but occurring in more shallow crustal levels. The subduction of a
Saxothuringian oceanic crust underneath the Tepla-Barrandian crust is responsible for the origin of a
magmatic arc represented by Devonian calc-alkaline orthogneisses and tonalities of the Central
Bohemian Magmatic Complex and by isolated granodiorite stocks intruding Neoproterozoic sediments.
At this stage the Barrandian basin operated as fore-arc domain as it is indicated by Devonian zircons in
the sediments of the same age in the Prague basin. It is difficult to evaluate the original depositional
origin of Moldanubian metasediments, metabasites and other high grade rocks due to severe and
polyphase reworking.
9
Fig.5 Geodynamics of the Bohemian Massif
The first belt, recognized west of the magmatic arc, was exhumed along huge west dipping
detachment zone, which was also responsible for collapse of the upper part of the magmatic arc system
and downthrow of the whole Barrandian section. Such a huge vertical material transfer could have been
responsible for vertical exchange of lower crustal and upper crustal material in a range of 50 km with
final throw of 15 km. The cooling ages from the lower crustal domain show that the granulites passed
the 300 °C isotherm during Carboniferous, suggesting that the lower crustal bulge reached very shallow
position in the upper plate. The second lower crustal belt rims the eastern margin of the Bohemian
Massif, i.e. the boundary with the Brunia continent. Here the fabric of granulites is also vertical and is
interpreted in terms of massive vertical exchanges with orogenic middle crust. The zone of lower crustal
bulge is interpreted as enormous anticline extrusion surrounded by middle crust coevally transported
downwards in form of huge crustal scale synforms. The model of vertical extrusion is based on the
concept of buckling of lower and mid-crustal interface followed by growth of crustal scale antiforms.
This process is thought to be triggered by rheological and thermal instabilities in the arc region, while
to the east it is forced by rigid back-stop, preserved only locally.
10
However, the most important feature of the eastern Variscan front is the development of
horizontal fabrics in the Moldanubian root zone, parallel to the Brunia continental margin. The intense
deformation of the Brunia leading to the formation of Moravo-Silesian imbricated nappe system, the
origin of crustal mélange forming the Moravian micaschist zone and mixed high-pressure rocks and
migmatites in the overlying Moldanubian nappe have been recently interpreted in terms of indentation
of the Brunia continent into the hot and thick continental root. This lower crustal indentation and flow
of hot lower crustal rocks in supracrustal levels are consistent with the model of continental channel
flow driven by arrival of crustal plunger, a model which is advocated for two decades for the deformation
of the Eastern Cordillera in the Andes. Finally, the load of Brunia platform related to deep indentation
process, leads to the development and easterly propagation of the foreland basin associated with
progressive involvement of the early clastic basin infill into the channel flow process. In our model
(Schulmann et al., 2008) as the hot Moldanubian rocks advances over the Brunia platform, the imbricate
footwall nappe system of the Moravian zone is generated and thrust over the foreland basin rocks.
4. Mokrsko Au deposit (Psi hory gold district) - day 1
Location:
The Psí hory gold-bearing ore district is situated at the Central Bohemian region, approximately 50 km
south of the city of Prague. The eastern side of the ore district is bordered by the river of Vltava, or more
precisely by the water reservoir Slapy.
Geological characteristic:
Fig.6 Geological map of Psí
hory gold- bearing ore district
11
The Psí hory gold-bearing ore district is built by contact zone of Variscan Sázava intrusion (the Central
Bohemian Pluton /e.g. Janoušek et al. 2004/) and Neoproterozoic volcano-sedimentary rocks of the
Jílové Belt (Fig.6) and it consists of three main ore bodies - Čelina, Mokrsko-West and Mokrsko-East.
The largest and the most significant is the Mokrsko-West gold deposit, well known for its typical gold-
bearing structures - a system of massive parallel sheeted thin quartz veins developed along E-W striking
microfissure system (Morávek et al.1996). According Boiron et al. (2001) associated fluids were trapped
at 350-450°C and 120-180 MPa and Zachariáš et al. (2014) assumes the deposit’s formation at a depth
of ≥9 km. The larger part of Mokrsko-West deposit lies in the apical part of Sázava intrusion (amphibole-
biotite tonalite) and only smaller part is situated at zone of contact metamorphosed volcano-sedimentary
sequences. The gold (native gold with
high fitness and gold phases with Bi-Te-
Sb) is mostly finely dispersed in quartz
and arsenopyrite (e.g. Zachariáš et al.
2014). Other accompanied mineral
phases (not economically exploitable) are
represented by scheelite, arsenopyrite,
pyrite, pyrrhotite and molybdenite.
Mokrsko-West can be described as near
surface (Fig.7), low-grade (2 ppm) gold
deposit with proved reserves to 90 tons of
gold (Morávek 2013). According
Zachariáš et al. (2014) Mokrsko-West
shares the features of both intrusions
related gold and orogenic gold deposit.
The both Čelina and Mokrsko-East
deposit is formed by volcano-sedimentary
rocks of Jílové Belt and the gold is hosted
by thicker quartz veins. Sheeted quartz
vein system was not developed here. The
Čelina has reserves about 11 tons of gold
and Mokrsko-East reserves reaches 29
tons of gold (Morávek 2013).
Fig.7 Cross section of Mokrsko West deposit
Mining history:
Only small scale historic mining took place at Čelina gold deposit, the Mokrsko-West deposit was
discovered during state sponsored exploration between 1980-1990. Exploration carried out regional soil
geochemistry and extensive drilling (35 km of drillholes, 8 km of underground galleries). Exploration
works led to definition of new gold-bearing ore district Psí hory. International competition was won by
company Rio Tinto Zinc, which obtain exploration licence, but it hasn’t a long duration. One problem
is the way, how the Mokrsko-West can be economical exploited, which is open pit mining and ore
processing by cyanide leaching. Second problem was problematic communication between involved
parties and the fact, that the countryside around the deposit is populated. Due to unresolved raw material
politics aspects, strong ecological and public protests, the licence was dropped off. The same problems
(poorly awareness about development and innovation in mining industry, unresolved raw material politic
and public protest) last until present day.
12
5. Roudny Au deposit - day 2
Location:
The Roudný deposit is located approximately 60 km SE from Prague and 12 km S from local town
Vlašim, Czech republic. Geologically it lies in the northern part of the Blanice Graben on its crustal-
scale brittle tectonic zone. This NNE–SSW-trending and ~200 km long tectonic zone crosses the Ostrong
and Drosendorf units (Varigiate series) of the Moldanubicum, and extends from east of Prague to Linz
in Austria.
Geological characteristics:
The broader area of Roudný deposit consists of
various rocks of Drosendorf unit. The most abundant
are sillimanite-biotite and biotite paragneiss. Gneisses
contain numerous small bodies of quartz-gneisses,
quartzites, calc-silicate rocks, amphibolites and
skarns. Veins of small younger aplites and pegmatites
are also frequent. The shape of ore body (Fig.8) forms
triangular cone prism with axis inclined 50-60° to the
WNW. Ore body is bordered by four brittle faults. The
horizontal length of the Roudný ore body along its
strike varies between 75 and 130 m, with a thickness
of 4-6 m. The presence of gold ores was verified to the
depth of 520 m. The ore mineralization is tied
especially to the Main vein (Fig.9) and surrounding
stockworks, some areas with ore impregnation in
altered rocks are also present. The Main vein is 0.1-
1.5 m thick, trending E – W or SE – NW. Bigger
veins are often massive or brecciated, smaller
veinlets are drusy. Mineral association includes 4
generations of pyrite, 2 generations of arsenopyrite
and 2 generations of gold. Chalcopyrite, marcasite,
sphalerite and galena are less frequent. Gangue
minerals are mostly quartz, carbonates, baryte and
fluorite. Gold is present as pure element or dispersed
in pyrite and arsenopyrite. The Au content usually
varies between 4-5 g/t, but some sections were very
rich with record value of 10.3 kg/t.
Mining history:
The first reports about mining in Roudný area are
from 14th century but the real bloom of mining
started in 18th century. In the second half of 18th
century the Roudný mine produced about 6 tons of
gold. Between years 1904 – 1930 was the Roudný
one of most modern gold mines in the Europe and produced over 80 % of gold in Austro-Hungarian
Empire, in total 5,8 tons in this period. Roudný mine had two shafts 450 m deep with 16 levels. Last
period of mining occurred between 1945 and 1956, depth of the mine reached 520 m, but the overall
productivity was low. Later Geoindustria exploration company made reevaluation of reserves, last
exploration was conducted in 1990. Modern technology allows mining of old tailings and upper part of
deposit with up to 2 g/t of gold, totalling in aprox. 800 kg of gold. However the further exploration or
mining is restricted due to present economical and above all political situation.
Fig.8 Cross section of the main ore body
Fig.9 Cross section of the „Main vein”
13
6. Krásná Hora - Milešov ore district - day 2
Location:
The Krásná hora ore district covers an area of 35 km2 between Krásná hora nad Vltavou, Milešov,
Proudkovice and Podmoky in Příbram district.
Geology:
The Krásná hora Au-Sb deposit is situated in a central part of the Central Bohemian Pluton (Variscan I-
type granitoids). The geological setting is very similar to that known from Mokrsko or Jílove Belt – in
low grade metamorphosed Proterozoic and Early Paleozoic volcanosedimentary assemblages intruded
by younger Variscan granitoids. Au and Sb vein-type mineralization is also adjacent to lamprophyres,
porphyrites and mylonite zone and is subdivided into the six main vein-type zones: Brtevnické, Zhořské,
Jamenské, Kobylská, Krasnohorské and Milešovské. Gangue mineral assemblages of the mineralized
veins consist of several generations of quartz and carbonates. The main ore mineral in the east and central
part of the deposit is stibnite, which contains scattered gold grains (> 1 mm). Another ore mineral is
aurostibite which occurs as pinkish reaction rim up to 3 mm thick around the gold grains. Beside stibnite
and aurostibnite, other minerals known at the deposit include common sulphides: pyrite, arsenopyrite
and accessory pyrrhotite, molybdenite, galena, sphalerite, chalcopyrite, antimony, chalcostibite,
tetraedrite and Sb-sulphosalts.
History:
The first published note on gold mining in the area comes from the years 1336-1338. Highest gold
concentrations were found in the oxidation and cementation zones those days. Latter in
1566 mining was terminated due to technical difficulties of needed underground mining in deeper parts
of the deposit. The second period of mining in the years 1850-1923 was focused on antimony and later
also gold in the galleries Jindřiška (1874), Marie (1884), Nová jáma /New Pit/ (1893) and Otto, situated
directly in the Krásná Hora nad Vltavou town (Fig. 10). During this period, 500 kg Au and 50,000 t Sb
was mined. After 1923, production declined. During World War II the deposit was again investigated
and new small but rich reserves of Au and Sb ore were identified. Last period of underground mining
began in 1985 and
ended in 1992. During
this period, 75,000 tons
of ore with typical
grade of 5.3 gpt of gold
and 1.9% of Sb, which
equals to
451 kg Au and 1480 t
Sb, was mined.
Stop-site situation:
The underground workings are not suitable for visit due to forbidden access. It is possible to visit one of
the main waste dumps (north of Milešov village) of country rock where ore remnants are still possible
to collect. Among the common sulphides and molybdenite, it’s also possible to find stibnite or even
visible gold with halo of aurostibnite.
(Fig.10) Cross section
of Marie and Nová
jáma galleries.
14
7. Jilove Au deposit - day 3
Location:
The Jilove gold district is located in central Bohemia approximately 20 km south of Prague, in the north-
east part of “Středočeska pahorkatina“ upland. The Jilove gold district (area of 20 km
2
), as a part of
regional-scale Jilove greenschist belt, hosts many of medieval to 19 century underground workings.
Geological characteristics:
The Jilove gold mining district is formed by volcano-sedimentary complexes of low-grade
metamorphism penetrated by Variscan contaminated I-type granites. Typical rocks of the Jilove Belt
are: a) metabasalts and metaandesites, turned to greenshists and locally contact metamorphosed to
hornblende-biotite hornfels, so called Spilite Group of the Jilove Belt and b) different varieties of I-type
granitoid of the Central Bohemian Pluton such as individual stocks to complicated vein systems in
reverse faults or extension fractures and/or stockworks in dykes and sheeted vein systems penetrating
both intrusive and upper crustal rocks,. The Jilove district is situated in the northernmost part of this
narrow, about 70 km long strip, trending NE-SW to NNE-SSW, which is a component of the south-
eastern limb of the Barrandian. Subordinately, the Jilove district is formed of the overlaying Algonkian
(Proterozoic) beds, and in the south-east contacts the granitoids of the Central Bohemian Pluton, which
at depth extend westwards below it. The hypabyssal intrusive rocks of Variscan age are of small extent
but of great importance for their structures and mineralization. Gold bearing impregnations in the Jilove
Belt rocks are formed of composite lodes and of quartz-pyrite impregnations of quite irregular shapes
without sharp contacts.
Mining history:
Ore bodies in the Jilove district have been operated for their gold content for almost one thousand years.
Mining boom in the Jilove district was in the first half of the14th century – mines reached a depth about
200 meters and aproximately 6-10 tons of gold was mined in this period. In the Hussite wars (beginng
of the 15th century) the mines was destroyed and all documents burnt. Between 1693-1768 was gold
exploited in the whole length of the Kocourkov zone to the depths corresponding to those of present
mines. In the 19th century was opened Pepř mine (Fig.11) in Studene (1830) and the Vaclav drainage
adit was driven from Sazava river (1828-1864). The amount of gold obtained in Jilove district can only
be estimated from the extent of the old mining works at X0 tons of gold. Since 1938 to 1969 was mine
works concentrated mostly in the south part of district in the mines Pepř, Stara jama, Nova jama
(Bohuliby) and
Radlik. Production
between 1958-1968
reached 1133 kg of
gold.
Fig.11 Cross-section
through the southern
part of the Jílové
district in the area of
the Pepř and Bohuliby
mines
15
8. Cinovec-Zinnwald Sn deposit - day 4
Location:
The Cinovec-Zinnwald deposit is situated on the border of Czech Republic and Saxony (Germany) in
the Krušne hory (Erzgebirge) region, which belongs to the Saxothuringian zone of Variscan orogeny.
Cinovec-Zinnwald is one of the most important deposits of the Bohemian Massif and is the “Locus
typicus” (type locality) of the Li-mica mineral Zinnwaldite.
Geological characteristic:
The mineralization in
the Cinovec-Zinnwald
mining district is related
to the late-Variscan
intrusion of the Krušne
hory/Erzgebirge granite
batholith, which
penetrates the Teplice
rhyolite. The country
rock of the magmatic
complex is two-mica
paragenesis of the
Krušne hory crystalline
complex. The highly
differenciated albite-
zinnwaldite granite in
the apical part of the
Cinovec intrusion hosts
a quartz-zinnwaldite
(topaz, scheelite) vein
system with Sn-W
mineralization (Fig. 12
and 13). Thickness of
the veins ranges from
0.2 to 2 m. Dip is conformable with the granite/rhyolite contact and varies in the range of 0-30°. The
veins are often surrounded by up to 20 m thick greisens with variable content of Sn and W. The situation
at the Cinovec-South deposit is different. The main mineralization is associated with greisens and
greisenized granites, with average grades of 0.2% Sn and 0.04% W. Moreover, the ore body contains Li,
Rb, Cs and Sc.
Fig.12 Geological
map of the
Cinovec de
p
osit
Fig.13 Cross section of the Cinovec deposit
16
Mining history:
The first historic record of mining activity in Cinovec-Zinnwald area comes from 1378. Since this time,
more or less intensive exploitation of the deposit lasted until 1990. The higher demand for tungsten in
the second half of the 19th century caused a mining bloom in the Cinovec-Zinnwald district, which
increased during the World Wars. After the WWII, the Czechoslovakian state company continued in
mining activity on the Czech side of the deposit (the German part was abandoned). Also extensive
drilling exploration was carried out at the same time (discovery of the Cinovec-South deposit). This
enabled a further mining after the northern part of the deposit got exhausted in 1979. The activity in the
last mining decade took place in the southern part of the deposit. The Czech part of the deposit was
mined underground with several historic shafts. The main shaft was 118 m deep, under this level the
deposit was opened with a complex of inclined shafts and adits to the deepest level of -284 m (550
m.a.s.l.). The overall length of the adits is more than 60 km. During the intensive mining activity in the
20th century, the overall production was more than 1.1 Mt of ore (2300 t of Sn and 1470 t of W).
Nowadays, several geological explorations are in progress in the Cinovec area. Cinovecka
deponie company obtained permission for lithium extraction from tailing pond sludge and Geomet
company runs exploration for underground mining of lithium, tin and tungsten (with also recovering
potassium sulphate during processing) in the Czech part of Cinovec deposit. Permission for small
exploration area is held by company Fluorit Teplice as well. In the German part, SolarWorld company
performs similar exploration works mostly focused on Li for bateries.
9. Krupka mining region - day 5
Location:
The Cinovec-Krupka mining region is situated in the eastern part of Krušne hory/Erzgebirge, close to
the Czech-German border. It is located approximately 6 km to the Northern direction from the Teplice
city.
Geological characteristic:
The strata surrounding the deposit are pre-Variscan crystalline paragneisses, orthogenesis and
metagranites. The deposit is associated with late carboniferous A-type granite intrusions, which belongs
to Teplice-Altenberg Caldera. These granites are categorized into (i) older biotite granite which forms
Preiselberg massif (NW of Krupka) and (ii) younger albite-zinnwaldite granite so called ,,Cinovec type“.
All the Rb-Li, Sn-W and Mo mineralization is genetically linked to the second granite type. In the
Krupka district, albite-zinnwaldite granite forms two prominent cupolas terminated by steep stocks with
intensive mineralization. The Preiselberg cupola lies at the contact of the Teplice rhyolite, the gneiss
complex and the Preiselberg biotite granite body, whereas the Knotl cupola lies 3 km to the SE, in the
gneisses. Both cupolas exhibit prominent vertical zoning. In the root zones they consist of the above-
mentioned medium-grained albite-zinnwaldite (Cinovec type) granite. Upwards, it passes into altered
(sericitized, kaolinized, hematitized, feldspathized) granites and finally into greisens. Formation of
pegmatite rims (stockscheider) and flat molybdenite-bearing quartz veins, parallel to granite-gneiss
contact is also characteristic (Fig. 14). Slightly younger steep veins are mineralized with cassiterite.
Mining history:
Krupka tin deposit is probably the oldest known tin deposit in Bohemia. The placers were worked here
as early as the Bronze Age, and primary ores since 13th century. Tin mining reached its peak in the 16th
century. During World War I, wolframite was exploited from the Lukas vein.
In the Knotl area, there is a huge number of a historical mining works. One of most significant
is Zwickenpinge dump in the vicinity of Barbara adit, which was established in 16th century and is one
of the oldest mining works in Krupka region. Molybdenum and ceramic feldspars started to be exploited
from the pegmatite body in Knotl during World War II and in the 1950´s respectively. Four adits were
17
opened in pegmatite part of Knotl cupola: Vecerni hvezda, Vaclav, Barbara and Prokop. However,
mining already finished there in 1956.
The Preiselberg cupola and associated greisen bodies and veins were intersected by several
galleries: lowest lying 5th May gallery (prospection 1970-1990), Stary Martin gallery (old mining) in its
overlying and No.2 gallery (prospection 1965-1970) at the very top. The Lukas vein, mined in the Martin
gallery, is around 2 km long and it is therefore the longest tin ore vein in Central Europe.
References
Wertich, V., J. Výravský, S. Hönig, V. Šešulka, M. Petržela, L. Losertová, P. Pořádek, S. Hreus. 2014.
Short Course in Gold Systems of the Bohemian Massif. May 5-9, 2014. Excursion Guide.
Masaryk University Brno SEG Student Chapter, 18 p.
Wertich, V., J. Výravský, M. Bošková, M. Cahová, K. Faktorová, T. Flégr, S. Hreus, Ľ. Kyrc, L.
Losertová, M. Patzel, M. Petržela, P. Pořádek, K. Sobek, M. Soukup, J. Šamánek, V. Šešulka,
S. Urbanová, J. Výravský, V. Wertich, A. Zachař. 2016. Mineral Deposits of the Krusne hory /
Erzgebirge. Apirl 25 - May 1, 2016. Excursion Guide. Masaryk University Brno SEG Student
Chapter, 39 p.
Fig. 14. Legend: 1-gneiss, 2-lamprophyre dykes, 3-Teplice rhyolite, 4-felsic granite porphyry, 5-marginal Preiselberg
granite, 6-Preiselberg granite, 7-albite-zinnwaldite granite, 8-albite-zinnwaldite aplite, 9-marginal pegmatite, 10-
quartz veins, partly with molybdenite, 11-greisenized granite, 12-greisen, 13-quarz veins with cassiterite, 14-quartz
veins with cassiterite and sulphides, 15-fluorite veins, 16-basaltic dykes, 17-faults. After Eisenreich and Breiter
(
1993
)
.