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Gold-bearing quartz veins may cut gneiss or schist, but often the veins parallel the bedding, or foliation. Carbonaceous phyllite/graphitic schist in the Archean Kundarkocha gold deposit 1695 Figure 2. Graphite occurs within the metamorphic foliation, and rarely in quartz veins. Tailings from the old processing plant contain some extremely high levels of reactive arsenic and antimony minerals, and are located beside the principal river. You do the math. Detecting hydrothermal graphite deposition during metamorphism and gold mineralisation. We also found silver, copper as native elements. Production between 1895-1938 gave 2.24 t of gold and 7.47 t of silver. Hence, graphite-bearing rocks in this area are of considerable interest, for gold exploration, and also to help to understand the processes of graphite enrichment and potentially associated gold enrichment. New Zealand, Tel +64 3 479 7519 Deposits are generally small (10 m scale), localised, irregular, and deposit locations are difficult to predict. Many of these micaceous schists are prominently enriched in graphite and pyrite. March 2004 by Edgar B. Heylmun, PhD. Microscopic view of a quartz vein (brown and white grains) in a late metamorphic shear zone (Jurassic) in the semischist faulted slice downstream of Fiddlers Flat. Accessories are: tetrahedrite, arsenopyrite, chalcopyrite, stibnite, galena, barite, gypsum. This is a very interesting gold specimen that originates from Northern California. PO Box 56 The polished surfaces also contain smears of metamorphic quartz, muscovite and chlorite. U.S. National Museum specimen (USNM) 66014 labeled "Montgomery Co., Maryland, gift of George Huddleston, 1880." Dunedin 9054 The carbon was transported as methane and carbon dioxide, and graphite deposition results from mixing these, and interaction with the rocks, probably during lowering temperature. Near-equilibrium metamorphic fluid-rock interaction and gold mineralization in the Otago Schist, New Zealand. Mineralium Deposita, Graphite and gold on the northeast schist margin, Find the Otago Students’ Geological Society on. Is gold-in-schist economic? Some of these pyritic graphitic schists are weakly enriched in arsenic, with As contents up to 60 parts per million, above a background 10-15 ppm As. Geology and Gold Mineralization around Kutcheri, northwestern Nigeria Amuda, A.K1, Danbatta, U ... metamorphism is of a higher temperature and lower pressure type than in other schist belts [2]. The strong enrichment of the rocks with graphite at Macraes is one of the defining features of that gold deposit. The blocks are separated by black foliated graphitic gouge, which forms polished surfaces on the blocks. A large sheared block of greywacke in a late metamorphic (Jurassic) shear zone in the broken formation fault slice at Fiddlers Flat. Alteration characteristics of gold mineralization throughout the Hattu schist belt gold occurrences are broadly similar, if less intense than the hydration, carbonation, and potassic alteration generally reported for Archean lode gold deposits. It is defined by having more than 50% platy and elongated minerals (such as micas or talc), often finely interleaved with quartz and feldspar. The gold occurs as micron sized grains in the pyrite and arsenopyrite. Gold grains are apparently elongated parallel to strong lineation in schist. The wetland discharges into the Taieri River, an important recreational and water supply river, but arsenic levels are low when the discharge reaches the river in normal rainfall seasons. This carbon mobility occurred through >50 million years of evolution of the metamorphic belt, from development of sheared argillite in the Jurassic, and was still happening when the middle Cretaceous extensional faults developed about 110-120 million years ago. ... Cameron’s Line is about two miles west of the Rowe schist the formation that underlies the property belonging to the finder of the Whodunit Mine. 13. Large graphite grains occur in the recrystallised vein quartz, where they are up to 1 mm across. © Department of Geology Gold (Au) in sheeted vein quartz with schist partings (S). New Zealand, Tel +64 3 479 7519 Metamorphic rocks such as gneiss and schist are known for their pocket gold deposits. 12. Gold-bearing quartz vein, Shotover, Otago, Gold (yellow dots, centre) in sulphide minerals, Stibnite, Sb2S3, from Nenthorn goldfield, Otago, Compositions of mine waters around schist-hosted deposits (red bars) compared to drinking water limits (blue boxes), Arsenic at Barewood mining area, east Otago. This nugget was also found in the Bradshaw Mountain Range. If you compress mud (underneath the weight of the ocean and a whole lot of other mud) you get shale. 1). The nugget was found with the Coiltek Wallaby Mono & GP3000 metal detector. deposits in the Mid-Bosnian Schist Mountains area. Microscopic view of a vein (1 mm wide) with graphite (black) and quartz (white) cuts across sheared greywacke in the broken formation fault slice at Fiddlers Flat. Craw D, Henne A, Upton P 2010. Historic mining of schist-hosted gold has exposed arsenic-bearing rock and discharged arsenic-bearing tailings to a stream which has now become a wetland. Antimony has been mined historically from some localities of this type of deposit, but never profitably. As its name implies, this type of schist also contains significant amounts of sericite, which is a fine-grained type of either muscovite or paragonite, both of which are relatively abundant silicate minerals. Micas, feldspars, and quartz usually account for most of the minerals present in a schist. Deposits are largely restricted to the South Island, and are scattered through Otago, Marlborough, and northern Westland. This specific piece is from a core sample extracted from the EMPIRE MI Possibly from Huddleston mine (fig. Here is a wealth of information on locations you can search for placer gold, including great places to camp with your family in California, Alaska, Nevada and Arizona and elsewhere. Bulk carbon contents range up to 5 % and sulfur contents range up to 11 % for these micaceous schists. High grade gold in quartz rocks! Craw, D. 2002. FireFox Gold Corp. is pleased to report that it has incorporated two new tenement blocks, collectively called the Kierinki Project into its gold exploration portfolio in central Lapland, Finland. Location of Endeavour Inlet (right), and a detailed map of the area (left), Historic antimony smelter tailings, Endeavour Inlet, © Department of Geology Gold, on top of being rare to find, spawns in one of two stone variants; one of which is hard to mine. This graphite was introduced via hot water but has since been recrystallized. On-going deformation, both ductile and brittle, resulted in remobilisation of gold, sulphides, and graphite. Arsenic in soil and wetland sediment is strongly elevated (to >1000 mg/kg) above regional background of 10 mg/kg. Fax +64 3 479 7527 Harvesting. Gold occurs in two distinct geological settings in Otago: within quartz veins in the schist (hard-rock gold), and as detrital gold grains in gravels (alluvial gold). These deposits formed by hot water moving through rocks as the surrounding rocks were uplifted from deep (10 km) in the Earth's crust. Find the Otago Students’ Geological Society on. Metamorphic > Schist (Amphibolite) Dominantly dark basic rocks including biotite, amphibolite, and graphitic schists and crystalline limestone also light-colored feldspathic bands resembling quartzite. Does most placer gold weather from gold -in-schist rather than from quartz veins? Maoduqing gold deposit occurred in the green schist and marble stratum belt of paleoprotozoic Inner Mongolia. Groundwater emerging from old underground mines has strongly elevated arsenic and antimony. Characteristic features of these deposits are listed below. Graphitic shears bend around resistant blocks of sandstone and conglomerate which are embedded in sheared greywacke and argillite, as in the photograph below. The  ductile foliation is strongly defined by graphite-rich seams, with grains that range in size from micron-scale dusty material to 0.3 mm. Pitcairn, I K, Roberts, S, Teagle, D A H & Craw, D. 2005. The carbon was redeposited as coarser grained graphite, especially in the shear zones (as in above photographs) along which fluid flowed most readily. Thin black seams are rich in graphite that was introduced into the rock by hot water during deformation. Mining costs are rocketing. A sample described by Barnes composed of anthophyllite, plagioclase, and biotite. Gold occurs with quartz "reefs" or veins in cracks in the rock (mainly schist). Maps of arsenic concentration in soils (left) and water (right) in the Barewood wetland. All About Placer Mining Placer nuggets are the goal of many prospectors. Is gold present in schist ductile or brittle stage ? The highest grade schists in this section are similar to those that host the Macraes gold mine. Gold is hard to find, and you have to find the right location to prospect if you are going to be successful in your search for gold. Gold mineralisation at Oturehua was controlled by northwest-striking normal faults that developed from coalescence of scattered, steeply dipping extensional fractures in lower greenschist facies schist. Email geology@otago.ac.nz, Structure, Environment, Reaction, Petrology, Geology along the Otago Central Rail Trail, Introduction to metals in the New Zealand Environment, Antimony mobilisation from mineral deposits in schist and greywacke, Mobilisation and dispersal of antimony from antimony-gold mineral deposits, NZTEG 2008 - Antimony in the New Zealand environment, Heavy metal discharge from fossil hot springs, Active analogies for old hot spring systems. Proceedings of 11th Biennial SGA Meeting, Antofagasta, Chile, pp 529-531. Dunedin 9054 The block is covered with sheared graphite-rich material that was introduced into the rock with hot water flowing during deformation. Deposits are generally small (10 m scale), localised, irregular, and deposit locations are difficult to predict. Microscopic view of pyrite (FeS2) and arsenopyrite (FeAsS) grains (black, 2 mm across) in ore grade schist from Macraes gold mine. Figure 3 Examples of historic (>100 year old) mine tunnels driven Deposits are largely restricted to the South Island, and are scattered through Otago, Marlborough, and northern Westland. The metals in the deposits were extracted from the surrounding rocks by dissolving trace amounts from a large volume of rocks. Microscopic view of pyrite (FeS2) and arsenopyrite (FeAsS) grains (black, 2 mm across) in ore grade schist from Macraes gold mine. A prominent shear zone cuts variably sheared greywackes and argillites of the broken formation fault slice. Hence, rocks rich in graphite are potential targets for gold exploration, especially in schist belts such as Otago Schist. Eluvial gold occurs within Maru schist belt in some locations called minor gold fields and has been recovered by artisanal miners through excavation of several pits of various dimensions and depths. A heavily mineralized schist zone with pyrite veins found as a stockwork deposit. The margins of these ductile shears have been brecciated in a brittle manner, and the breccias have been partially reactivated to form soft gouge that is part of the major nearby Cretaceous normal fault zone. Dark horizontal seams are largely graphite aligned in the shear foliation. This piece was almost a solid one ounce of gold. Gold-bearing veins in the Klondike schist are hosted primarily in extensional sites associated with post-metamorphic compressional structures. In fact, schist was boring mud before metamorphic forces got to it. The semischist slice includes some schistose micaceous rocks with abundant pyrite and/or graphite. EMPIRE MINE Gold In Schist Specimen: 3.8 Grams This RARE Gold in Schist Specimen is one of the few remarkable pieces of its kind! Rare mercury bearing deposits occur in Otago. Black rectangles are pyrite (FeS2), typically 1-2 mm across. The river with elevated As and Sb discharges to farmland and the Queen Charlotte Track, a popular tourist walk. Many streams and the principal river have naturally elevated As and Sb.

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