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 Faculty of Science, Charles University in Prague, Albertov 6- Whereabouts, transport, dining etc.
This article is a short guide for Prague newcoming visitors. Given information should help to navigate you around and also help you to find a suitable way to the faculty at Albertov 6,or other significant waypoints during your visit.
1) Vaclav Havel Airport- Faculty of Science, Albertov 6
The airport is located on the outer east side of the city, the way to the Faculty can take up to an hour. In case you head to your accomodations first, follow this instruction to get to the underground metro station line and customize your path afterwards. Faculty is several minutes from Tram station Albertov (see map)
-After your check-in at the airport, find Terminál 1 it is a waypoint to get your bus to metro station (underground line) Nádraží Veleslavín.
– Get off the bus at Nádraží Veleslavín station and enter underground line in direction Depo Hostivař and transfer for tram at station Malostranská.
– Exit Malostranská station and get to the ground level. Use the left exit to get to nearby tram station with the same name. Take tram no. 18 to the station Albertov.
Faculty
– located several minutes walk from the station. Turn to the perpendicular wide street in between both tram stations and walk to the end of Albertov street. Entrance is from the main street, last building on the right side. In case ask for Albertov building 6.
Pics:
Airport map
Map of transportation services
Transport line from Airport to Faculty
Tram- Faculty map
Faculty location: Albertov 6
2) Dining, shops, restaurants
Besides Icebreaker party and coffee breaks, food and drink is not provided by the organizers of the Shortcourse.
Several options are aviable in surrounding area of the Faculty. You can either choose to visit one of the restaurants and bufées or go shopping at nearby supermarket.
Supermarkets and malls
Lidl supermarket: is walking distance from faculty, turn left from Albertov street and follow the tram line. The market is minute away from tram station (by the church ) Atrium mall: is located at Karlovo Náměstí: (square, also metro station) small shopping passage with supermarket as well. Quadrio mall: Large multi level shopping mall right atop Národní třída metro station. 10/15min from faculty.
Restaurants
Best way is to ask around, organizers or othe colleauges can be helpful
Comments Off on Field trip: Heritage stones of N part of Bohemian massif
Date:
October 19-20, 2017
Program:
First day we visited famous heritage stones deposits: Ruprechtice
(typical granit deposit “Liberecká žula”) and Spa Bělohrad –
quarry Javorka (nicely coloured sandstones). Then we moved to Hořice
town, famous by its sculpture school, which we also visited. Here we
joined the lecture about “How the statue is made” and also seen
different processes and approaches of making statues. Besides the
school we also visited a famous park and graveyard with many
sculpture works (many times made by famous sculptors) from local
school.
Comments Off on Field trip and conference: Various deposits of the South Karelia region (Sortavala- Pitkäranta) – joined field trip with the SGA Student Chapter – North-West Russia
Date:
October 3-9, 2017
Program:
Presentation of poster at student conference of St. Petersburg
University. Excursion about heritage stones in St. Petersburg. Field
trip in Karelia region with various types of deposits (different
zones of skarns, marble and rapakivi granite used as heritage stone,
nice samples of almandines in micashist and visit of central uplift
island in Yanis”Yarvi lake made after impact).
)
