Comments Off on Fieldtrip report: Zlaté Hory deposits and history of mining
Fig. 1: Participants of the fieldtrip. Photo by V. Santolík.
At the end of October 2021, the SGA student chapter in Prague held a three-day autumn excursion focused on a mining district Zlaté Hory in Jeseníky mountains and its surroundings. The area is composed of Variscan metamorphic rocks like phyllite, micaschist, paragneiss, orthogneiss, amphibolite and limestone, which were formed from Cadomian (~570 Ma) to Variscan (~300 Ma) times. The polymetallic VHMS deposit occurs in metamorphosed Devonian formations and is currently a matter of exploration for possible gold mining.
1st day. History of Au, Fe and Mo mining in the Zlaté Hory region.
The first day was focused on surface signs of previous mining and was lead by Dr. Josef Večeřa. These are dominated by placer mining marks like pits, hollows and canals as well as underground mining marks like pits and adits. The researchers were able to define three stages of mining based on different mining techniques – medieval, modern and 19th century. Interestingly, the different stages are commonly seen at a single locality. For example, in Hláska forest near Ludvíkov village, there are several pits following a single ore bearing structure and depending on the distance between particular pits, it can be inferred, whether they correspond to the medieval or modern period. Consequently, we visited a locality near Vidly village where we found several minerals related to iron ore which was mined until 18th century, including magnetite, hematite, specularite and jasper.
2nd day. Minerals collecting in mine Zlaté Hory – west; “Blue drift”.
On the second day, we went down into the Zlaté Hory – west mine, where the current exploration takes place. The walk to the end of the drift was nearly 4 km long, unfortunately the oxygen level detector did not allow us to stay there for a longer time and search for minerals. However, during the 4-kilometer walk we still managed to find several appealing minerals, for instance pyrite, galena, sphalerite, cerussite and copper. On the way back, we entered the “Blue Drift”, which is called blue for the intriguing blue colored allophane covering the walls. After a few hours in the mine, we visited local museum with a nice exposition of minerals and rocks found in the area.
Fig. 2: Azure blue allophane covering walls in the “Blue Drift”. Photo by V. Santolík.
3rd day. History of mining – open-air museum.
On the third day morning, we visited an outdoor museum dedicated to old miners and old mining techniques. We learned about their lifestyle and tools they used for daily life as well as the methods and equipment applied for gold obtainment. At the end, we were encouraged to find some gold with a gold washing pan in the arranged containers with sand and water. The most adventurous of us could not resist despite the freezing water and managed to find a few gold grains. Finally, with minds full of new experience and bags full of new minerals, we returned back home.
Fig. 3: Gold mining open-air museum in Zlaté Hory. Photo by V. Santolík.Fig. 4: Collected quartz sample with a native gold. The biggest gold has a size of 200 µm. Photo by M. Tuhý.
Děkujeme IGCP 682 – MINE TAILING REVALORIZATION (Duration: 2019-2021) za finanční podporu, která přispěla k organizaci této exkurze / We thank IGCP 682 – MINE TAILING REVALORIZATION (Duration: 2019-2021) for its financial support, which helped to organise this excursion.
Comments Off on Obnova členství/Renewal of membership
*English version see below
Kvůli pandemii COVID-19 členské příspěvky letos nebudeme vybírat na vánočním večírku (žádný se konat nebude). Členské příspěvky nám zašlete na účet a to nejpozději do 30.12.2020. Do zprávy pro příjemce pak vyplňte své jméno (pokud jméno nevyplníte, peníze propadnou do pokladny SGA). Vzor viz níže.
Due to pandemic situation we are not able to take out money for prolonging your membership on christmass party (there won´t be any). Send us your membership fee on our bank account (pattern see below) by 30.12.2020. Into the message for receiver fill your name (in the case you won´t do so, money money will be added to SGA account).
Vzor/Pattern
účet/account:2058839019/3030
cena/price: 260 Kč (10 Euro)
zpráva pro příjemce/message for receiver: Vaše jméno/Your name
do/by 30.12.20 !!!
Nejste ještě členy SGA? Přidejte se k nám! Stačí vyplňenou přihlášku poslat našemu prezidentovi na email (jaromers@natur.cuni.cz) a zároveň poslat členský příspěvek na již zmíněný bankovní účet.
You are not a member of SGA? Join us now! Send filled application to our president on email (jaromers@natur.cuni.cz) and send membership fee on already mentioned bank account.
Přihláška pro zájemce/Application form for new members:
Štěpán Jaroměřský; Karolína Fizková; Jan Šulc; Štěpán Dvořák; Marek Tuhý
Faculty of Science, Charles University, 128 43 Praha 2, Czech Republic; Corresponding author E-mail address: jaromers@natur.cuni.cz
Fig. 1: Ongoing lecture; Photo by Štěpán Jaroměřský
On 30th July was organized, despite some restrictions caused by the pandemic, excursion to South Bohemia. 15 Chapter members took part in this 1-day excursion. The expert interpretation was led by Mgr. Miloš Faltus, Ph.D. (Fig. 1). The aim of the excursion was to introduce the participants to the Czech rarity in the form of tectite called Moldavite. As one of the few people we were given the opportunity to look into the sand pit (Fig. 2), which is located between the village of Chlum and Ločenice. This sand pit is mainly used for sand mining, but its secondary product are the Moldavites (Fig. 3). It is the only company in the Czech Republic that has permission to officially mine and then sell Moldavites
Fig. 2: View of the sandpit; Photo by Jan ŠulcFig. 3: Active treatment plant; Photo by Jan Šulc
The first discovery of Moldavites was in 1787 by Dr. Josef Mayer from Charles University. He had thought of them as glass of volcanic origin. They were named after the Vltava River, around which the first findings were located. Later, the concept of Moldavite was introduced from German Moldau (Vltava). As similar glasses were later found more widely around the world, the common international name of tectite (from Greek tectose – fused) was also used for them. Generally they are vitreous bodies, which usually have dimensions of several centimeters and a weight of several units up to tens of grams. Tectites can be found all over the world, but Czech Moldavites, unlike others, have a transparent light or dark green colour.
Today, the most likely and widely accepted theory of the formation of Moldavites is considered to be the impact of a meteorite on the surface of the Earth some 14.5 million years ago. This impact occurred in the area of today’s so-called The Ries crater between Norimberk, Stuttgart and Munich. Today in the centre of this crater lies the city of Nördlingen. The Ries crater is 24 km in diameter. The meteorite impact occurred at a speed of about 20 km/s, at an impact angle of 30-50 °. During the collision with the Earth, a huge amount of energy was transferred, resulting in the crushing, melting and evaporation of rocks at the point of impact as well as a separate cosmic body. There was a cloud containing gaseous, liquid and solid phases, the main part of which was directed to the East. When the initial high temperature and pressure dropped, the silicate melt solidified so quickly that the individual mineral components did not fully crystallize to form silicate glass. This was particularly the case in the area of southern Bohemia and southern Moravia in the vicinity of Trebic. The range of the vltavins from Ries crater to southern Bohemia and southern Moravia was 200-450 km. It is estimated that the total weight of all fallen vltavins would be about 3000 tonnes.
Fig. 4: Currently found moldavite; Photo by Jan Šulc
South Bohemian Moldavite is characterised by its light – dark green colour. This is different from the Moravian ones, which tend to be in brown colours. Very rarely was also discovered bicolor moldavites, probably due to the combination of two distinct moltens before impact. Chemically, it is silicate glass, except for SiO2, which is 70-80 % represented in moltens, we can find Al2O3 in the composition. MgO, CaO or Fe oxides. The hardness varies between 6 and 7 of Mohs scale
Macroscopically, they have a very peculiar appearance and they are mostly in the shape of balls, sticks, droplets, also rarely for heart or hedgehog shapes (Fig. 5). A great interest is the sculpture, which occurs mainly on the Moldavites from southern Bohemia. This is the name of the surface of the individual samples, which has been disturbed by the acids contained in the soils. These acids then stick to the surface of the Moldavite over time, resulting in a certain wrinkling of the surface, which is quite valued. Moldavites also contain a number of inclusions, which take the form of closed-gas bubbles. Because the Moldavite is chemically very close to the glass, it is sometimes difficult to distinguish the cutted Moldavite from the cutted green glass.
Fig. 5: Rare hedgehog Moldavite form; Taken over: http://observatory.cz/static/vystavy/vltaviny/4-vltaviny.php
The sand pit, which we visited as part of our excursion, belongs geologically to the South Bohemian basins, where sedimentation began during the Cretaceous period and continued until the Tertiary. The basins are composed primarily of fluvial and lake sediments. In the visited sand pit we find Moldavites in the Domanín formation, in the Korosec series, in sands to gravel with clay inserts. Moldavites are a rare mineral, and a lot of people want them to make money. In most cases, they dig even a few meters deep pits (Fig. 6) to get into the layers that contain the Moldavites. Unfortunately, this intervention often destroys nature, natural root systems and endangers animal safety. This problem has been solved for several years and is likely to be solved by extracting all layers with Moldavite findings (except fields) followed by rehabilitation to the original natural conditions.
Fig. 6: Consequences of illegal mining; Photo by Jan Šulc
The whole excursion was a great success and we would like to thank the owner of the sand pit Ing. Viktor Weiss, who allowed us to enter the normally inaccessible area. We would also like to thank Mgr. Miloš Faltus, Ph.D., who gave us a professional lecture and last but not least, we would like to thank the entire SGA for our long-standing support and favor
Baier, J. (2009). Zur Herkunft und Bedeutung der Ries-Auswurfprodukte für den Impakt-Mechanismus. Jahresberichte und Mitteilungen des Oberrheinischen Geologischen Vereins, 9-29.
Baier, J. (2007). Die Auswurfprodukte des Ries-Impakts, Deutschland. Verlag Documenta Naturae.
Vand, V. (2009). O původu tektitů a vltavínů. Pokroky matematiky, fyziky a astronomie, 54(1), 23-32.
Řanda, Z., Mizera, J., Frána, J., & Kučera, J. (2008). Geochemical characterization of moldavites from a new locality, the Cheb Basin, Czech Republic. Meteoritics & Planetary Science, 43(3), 461-477.
Skála, R., Strnad, L., McCammon, C., & Čada, M. (2009). Moldavites from the Cheb Basin, Czech Republic. Geochimica et Cosmochimica Acta, 73(4), 1145-1179.
Comments Off on Prague SGA Student Chapter visiting Columbia-Bogotá SGA Student Chapter: Mineral deposits of Columbia
Štěpán
Jaroměřský, Ivan Mateo Espinel Pachón, Jan Hofmann, Milton A.
Santos
1SGA
Student Chapter Prague, Faculty of Science, Charles University,
Albertov 6, 128 43 Prague 2, Czech Republic; jaromers@natur.cuni.cz
Photo of the whole group of participating members
As
every year, Prague Chapter participates in several fieldtrips with
friendly chapters. This year, we managed to negotiate several daily
fieldtrips with the SGA Student Chapter Columbia-Bogotá, which
should have focused on emerald and gold deposits. The main target was
to visit the world famous emerald deposit near the town of Muzo.
However, the whole program was charged and very well prepared by the
Colombia-Bogotá Chapter. The Prague chapter was represented by 10
members and the field trip lasted from March 19 to 25.
1st
day:
On
the first day we visited a sedimentary-exhaliative deposit (SedEx)
near Chiquinquirá – Boyaca. Sedex are ore deposits formed by a
release of ore-bearing hydrothermal fluids. Subsequently, they must
be released into a water reservoir, resulting in the precipitation of
stratiform ore. SedEx deposits are the most important sources of
lead, zinc and barite. These ores are processed for tungsten, copper,
silver, gold and bismuth.
This deposit is located high in the mountains of northern side of central Colombia. 10-year-old exploration galleries designated for researching copper in the past surround the site. There are abundantly chalky sediments, in which there are minerals of copper such as chalcopyrite. We also found some beautiful examples of barite crystals. It is a fairly extensive site, but because of the steep slope and dense fog, we stayed on the upper parts of this deposit. It was a nice introduction to Colombian geology and nature.
2nd
day:
On
the second day, our emerald trip started in Las Pavas area. We had
accommodation in the town of Muzo, from where a very narrow path led
through the local mountains. Muzo itself is well known for its
emerald deposits.
Emeralds
are usually found in calcite-dolomitic veins containing pyrite,
ankerite, albite and quartz. These veins are the product of
hydro-thermal fluids that disrupt the rock massif and the
interactions of the metasomatic fluid with subsequent deposition in
the breaks formed by these calcite-dolomitic veins. It is likely that
metasomatic fluids come from shale formations near Muzo, which are
probably the source of vanadium, which is the cause of the unique
color of local emeralds.
Firstly,
we headed to the Rio Magdalena where we could find some samples in
the river or meander scrolls. Only one member of our chapter was
lucky enough to find a small sample in the shale. We even
investigated one closed mine which might be reopened in the near
future.
Fine emeralds crystals from Muzo. Photo by E. Vrňatová
3rd
day:
On
the third day, we had a scheduled visit to El Líbano Tolima, the El
Porvenir gold mine, orogenic and epithermal gold deposit. This mine
is processing sulphide ores like pyrit, containing relatively large
amounts of gold (up to 1000 ppm). The grains of gold in the bearing
are mainly included in sulphides and silicates. The mineralization of
gold in the bearing is probably caused by the penetration of
porphyres into the Paleozoic slate on the eastern wing of Colombian
Andes. It is believed that the mineralization of gold occurred in
three early phases of intrusion, which are accompanied by a number of
sodo-calcical changes and the late phase of penetration of porphyres.
The samples contained high quartz and chalcopyrite content.
We
travelled to the mine a long way on a car’s hull. Then we went
through the inspection, which was waiting for us in front of mine.
The whole mine is active and so we could only be there in the pause
period. The whole visit was fantastic and very engaging. At the end,
everyone could take only one sample of the size of a fist.
One of the eight entrace to the El Porvenir gold mine
4th
day:
On
the fourth day, we visited the Cu-skarn Payandé deposit with
garnets.
The
post-Triasic plutonic rocks, known as the Payande Stock, grow on the
eastern edge of Colombian central Cordillery near San Luis-Tolima.
The quarry could not be reached directly by our bus, so we had to
stretched our legs. At least we were accompanied by a car that eased
us from our backpacks and hammers. The road was not difficult, except
from the ford across the river, where we had to take off our shoes
and wade.
The reason why we drove there were skarn outcrops, where the great and beautiful crystals of andradite are located. Regarding the other minerals, hematite, azurite, quartz, calcite, chlorite, magnetite and sphalerite are also found here. Petrology and mineralogy is very interesting in this deposit, as there are signs of a passage of hydrothermal fluids and changing contacts with individual minerals. We saw the beautiful mineralization of the copper. There are also several zones to see. The first zone corresponds to the tonalites, the second to endoskarns and the third to exoskarns. There is also a prograde zone containing garnets and pyroxenes. In the retrograde zone, where iron oxides, iron sulphates and copper are found. This was our last locality in terrain.
5th
day:
On
the fifth day we were back in Bogóta and we had a planned tour of
the geological section at the Universidad Nacional de Colombia. We
went through some local classrooms and looked at a few samples from
the local collections. We also examined a few rocks which we saw
during the fieldtrip under a microscope and finally we listened to
short presentations from Prague Chapter and Bogota Chapter. After
exploring the area, we went to the city to taste a bit of all
possible and impossible fruits on the world-famous market Plaza de
Paloquemao. Then we moved to the Gold Museum in Bogota and the
largest Emerald museum in the world. Unfortunately, this day the
Emerald Museum was closed in, so we had to visited another day.
Finally,
we would like to thank all the leaders of this fieldtrip, especially
Ivan Mateo Espinel Pachón and all the SGA Student Chapter
Columbia-Bogotá members for an amazing organization and for ensuring
everything needed for the success of fieldtrip. In general, I think
that the cooperation between Chapters is the best form of studying.
Also I would like to express great thanks to the whole SGA, as it
would not be organized without their support and many thanks to all
our sponsors, such as Vitana or Severočeská doly.
I
think that this fieldtrip to Columbia strengthened the connection
between our SGA student chapters and we hope that despite the
distance between Prague and Colombia we will continue to collaborate
and exchange experiences.
Comments Off on Traditional autumn field trip: Various metal, precious stone and heritage stone deposits of central and east Slovakia
1 st day: Dřínová quarry (duplex structure with nice samples of barites in limestones) and visit of mineralogical exposition in gallery Patriot in Tišnov. 2 nd day: Špania Dolina area in the central Slovakia (heap with celestines samples, Piesky locality with azurite samples and Richtarova loc. which is type locality for deviline) and visit of Dobšiná with ongoing research of Ni and Co deposits. 3 rd day: Gretla (spekularite and goethite deposit), Novoveska huta (heap Bartolomejka with tyrolite and other Cu secondary minerals) and mine Josef close to Dubnik, where is gem quality opal deposit. 4 th day: open pit mine Fintice close to Přerov (andesites with zeolite samples) Leader: Bc. Jakub Mysliveček (Czech Geological Survey)
Comments Off on Gold Short Course 2018 (Prof. David I. Groves)
We would like to thank you all for participation at two-day Gold Short Course by Prof. David I. Groves and we are looking forward seeing you again! Please find our online gallery with photos fromshort course and post-course field trip.
We would like to invite you to a two-day Gold Short Course by Prof. David I. Growes from the Centre for Exploration Targeting, UWA, Australia. The course will take place on the 19th-20th May 2018 in the building of the Faculty of Science, Charles University in Prague, Albertov 6. The ice-breaker is planned for the evening of 18th May (Friday), start at 5 pm. Attendance on the short course is for free thanks to SGA Educational Fund, but the field trip is charged by 160 EUR for SGA members and 280 for non-members.
For any question about the Gold Short Course please contact us on gold.course.prague@gmail.com. Registration form for Gold Short Course and information about our post-short course field trip please find in the links below.
Please send your registrations on the email above. (In case of not responding please try to contact us on our personal emails).
Schedule of Gold Short Course
Saturday
OROGENIC GOLD DEPOSITS
Before 9 am: morning coffee
9:00- 1st lecture: Introduction to orogenic gold
10:35- coffee break
10:55- 2nd lecture: The crustal continuum and genetic models for orogenic gold
12:30- lunch time
14:30- 3rd lecture: Critical factors controlling the formation of orogenic gold
16:05- coffee break
16:25- 4th lecture: Exploration targeting for orogenic gold
18:00- expected end of the Saturday program
Sunday
GOLD DEPOSITS ON CRATON MARGINS
Before 9 am: morning coffee
9:00- 5th lecture: Introduction to intrusion-related gold deposits (IRGDs)
10:35- coffee break
10:55- 6th lecture: Nature of hybrid magmas and genesis of IRGDs
12:30- lunch time
14:30- 7th lecture: Carlin-type gold deposits of Nevada and China
16:05- coffee break
16:25- 8th lecture: Iron-oxide copper-gold deposits: nature and genesis
18:00- expected end of the Sunday program
*Cancelling with refund is possible only until two weeks before each trip.
**Organizers reserve the right to cancel a field trip for lack of participants.
***Besides Icebreaker party and coffee breaks, food and drink is not provided by the organizers of the Shortcourse.
Comments Off on Field trip to the central part of Krušné hory Mts. (Erzgebirge)
This two day field trip took place from 3th to 4th of June 2017 and was concipated to visit mainly Fe, Mn and fluorite deposits in the central part of Krušné hory Mts. (Erzgebirge) with some additional stops on other deposits.
First day:
We started the excursion in town Horní Blatná. Here we visited vein of Marie Terezie and heap of Concordia adit . Minerals occurring there were mostly Mn ore – pyroluzite. We found also quartz in small crystals up to 3 mm. Then we moved to „Ametystová Halže“ near Horní Halže village. This site is old mining part of Měděnec district and there is a large number of surface exposure of old mining activity. We found mostly amethyst and quartz crystals, ordinarily in clusters up to 7 cm and the primary Fe ores like limonite and pyrite.
After first part of the excursion we moved to rock formation called „Sphings“ near town Měděnec formed by very high pressure deformed „eyes-schist“ from Variscian orogeny processes.
From this place we could see landscape of Doupovské hory volcanic centre. Our another stop was at Mědník hill near town Měděnec. This small hill is the skarn body preparated by erosion in Quaternary and one of the most mined Fe and Cu deposit in early modern age. We ascended to the top of the hill around old skarn heaps and there was lecture about local mining from medieval to the end of 20th century.
Second day:
The weather condition did not allow us to see all three fluorite deposits in Krušné hory Mts. according to former plan, but only Hradiště fluorite deposit near Kadaň town and Kláštěrec nad Ohří town. This small deposit was mined for barite, fluorite and hematite. We found only fluorite and hematite samples. After that we moved to The Chateau at Klášterec nad Ohří town, where was also an exhibition of local minerals. We saw very nice samples of polished agates from Horní Halže village, Černý Potok vil., Ciboušov vil. and other sites.
After that we visited local spa area and we drank local hydrothermal water from the spring. This hydrothermal energy is caused by volcanic activity bound on Ohře rift and was formed mostly in Tertiary. Then we moved to quick visit of Ahníkov (former vil.) – site with minerals of weathering of laterites. We found specific minerals like white and purple chalcedone, green chryzotile and small crystals of quartz. After that we moved to our last site which was Lehnschafter adit in Mikulov town. Mikulov was mined mostly for Ag ores like Ag-rich galenite.
Eight Chapter members paticipated on this excurstion led by Bc. Jakub Mysliveček.
Comments Off on Field trip to the historical mining in Kutná hora and its surroundings
First day:
Visiting of adit St. Jiří in Oselské district – Medieval adit St. Jiří is a part of the mining-historical exhibition of the Czech Museum of Silver. This adit was discovered in 1967 during a hydrogeological survey and the length of its accessible part is about 280 metres. Quarry Práchovna – A new outdoor geological exposition was opened in August 2014 in the former quarry Práchovna. In this exposition are used a blocks of rocks from Kutná Hora area, Kolín and Chrudim with thematically structured panels.
The slag heaps – were deposited in the immediate vicinity of the silver smelter. The ironworks in the Vrchlice Valley were in operation from the 15th century until the end of the 18th century. This despite of the partialy flattened heaps, containing an estimated 400,000 tons of slag, are witnesses of the vast range of medieval metallurgical activity in the area. The St. Antonín Paduánský – is one of the most important mineralogical sites of the Kutná Hora region. The work followed a vein with a high content of antimony and silver ores. In the adit and in the dump we can get to know not only with typical veined minerals, but also with some luck we find rare silver ores. Our findings: berthierite, kutnohorite, pyrite, cave pearls. The site of the former RD Kutná Hora establishment – here is the Turkaňk mine, which draws the mined water treated in the built-up cleaner for user quality. A large basin in the southern part of the Turkaňk zone was created by the mines collapse in 1969. In the eastern wall of the basin is a gallery of an old mine about 100 m long. This old gallery belongs to the oldest phase of Kutná Hora mining.
Old heaps after mining of ores in the village of Kaňk – This dumps are an interesting occurrence of rare arsenic minerals. For the last two years, heaps have been involved in many pitfalls because they have been exposed to erosion or by targeting of the collectors. Hopefully, due to the timely intervention of the experts which was made, there will be no complete disposal of the heaps, as was previously thought. Our Findings: bukovskite, kaňkite.
Second day:
Malešov – a magnetite rich rock deposit opened by deep mines. Our findings: magnetite, garnet, pyroxene, amphibole, prehnite, calcite, epidote. Markovice – active amphibolite quarry near Čáslav. Known occurrences of alpine type minerals. Our Findings: prehnite, titanite, albite, calcite. Kožlí near Ledeč nad Sázavou – a small fluorite deposit with a high content of quartz. Our findings: fluorite, quartz.
Fourteen Chapter members participated on this excursion led by Mgr. Jan Bubal.
For more photos please visit this link.
