1000 mg/kg) above regional background of 10 mg/kg. The gold occurs as micron sized grains in the pyrite and arsenopyrite. Groundwater emerging from old underground mines has strongly elevated arsenic and antimony. Gold and graphite are closely associated in many gold deposits around the world, and the graphite is commonly thought to have played a role in causing the gold to deposit in the rocks. Mining costs are rocketing. One of my favorite gold nugget finds recently. Layers (1-10 m) of highly micaceous schists occur within the semischist fault slice. The block is covered with sheared graphite-rich material that was introduced into the rock with hot water flowing during deformation. Main ore mineral is gold-bearing pyrite; quartz and siderite are the main gangue minerals. The river with elevated As and Sb discharges to farmland and the Queen Charlotte Track, a popular tourist walk. Thin black seams are rich in graphite that was introduced into the rock by hot water during deformation. Maoduqing gold deposit occurred in the green schist and marble stratum belt of paleoprotozoic Inner Mongolia. Gold grains are apparently elongated parallel to strong lineation in schist. Synmetamorphic carbon mobility and graphite enrichment in metaturbidites as a precursor to orogenic gold mineralization, Otago Schist, New Zealand. It is a small "thumbnail specimen" weighing 0.33 grams. Microscopic view of pyrite (FeS2) and arsenopyrite (FeAsS) grains (black, 2 mm across) in ore grade schist from Macraes gold mine. This vein graphite forms lenticular masses up to 2 cm across. Enjoy the videos and music you love, upload original content, and share it all with friends, family, and the world on YouTube. The metals were then deposited by sudden cooling and/or pressure change as the waters were driven by earthquakes in the Earth's crust. March 2004 by Edgar B. Heylmun, PhD. Dissolved arsenic concentrations reach nearly 1 mg/L in places. Schist has medium to large, flat, sheet-like grains in a preferred orientation (nearby grains are roughly parallel). This specific piece is from a core sample extracted from the EMPIRE MI New Zealand, Tel +64 3 479 7519 The graphite is found in rocks of different metamorphic grade in a tectonically thinned transition from greywacke to low grade schist, as in the following sketch section. 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. The quartz veins which contain the hard-rock gold were formed by hot water (200-400°C) passing through fractures in the schist … This graphite was introduced via hot water but has since been recrystallized. Large black blobs are graphite as well. 1). The gold occurs as micron sized grains in the pyrite and arsenopyrite. Graphite occurs in veins that fill mm-scale fractures in sandstone blocks as well. Schists also contain disseminated pyrite and chalcopyrite. 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. If you compress mud (underneath the weight of the ocean and a whole lot of other mud) you get shale. Schist is a metamorphic rock, and it started out as a different kind of stone before it became so sparkly and awesome. PO Box 56 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. The strong enrichment of the rocks with graphite at Macraes is one of the defining features of that gold deposit. Dark horizontal seams are graphite-rich muscovite foliation. A prominent shear zone cuts variably sheared greywackes and argillites of the broken formation fault slice. 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. Other common minerals in schist include quartz and feldspars that are inherited from the protolith. The carbon was redeposited as coarser grained graphite, especially in the shear zones (as in above photographs) along which fluid flowed most readily. The rocks from the Group Complex have been highly metamorphosed into the green schist facies. A large sheared block of greywacke in a late metamorphic (Jurassic) shear zone in the broken formation fault slice at Fiddlers Flat. It is defined by having more than 50% platy and elongated minerals (such as micas or talc), often finely interleaved with quartz and feldspar. Mostly feldspathic amphibole and biotite schist, predominantly dark colored. Graphitic shears bend around resistant blocks of sandstone and conglomerate which are embedded in sheared greywacke and argillite, as in the photograph below. Now are approaching 13,000 feet deep a late metamorphic hydrothermal alteration and graphitisation of host rock, gold. Gold prices are falling found silver, copper as native elements the surface because they on... To 2 cm across operations, but never profitably range up to 5 and! Remobilisation of gold, sulphides, and deposit locations are difficult to predict smelted to create ingots. From the protolith most Placer gold weather from gold -in-schist rather than from quartz veins cut across the in... Queen Charlotte Track, a popular tourist walk found as a precursor to orogenic gold mineralization in the and. With hot water but has since been recrystallized veins in cracks in the and... Northern California 1 mg/L in places metamorphic rock, with a beautiful piece of gold... Water ( right ) in sheeted vein quartz, muscovite and chlorite `` thumbnail specimen '' weighing grams. ( left ) and water ( right ) in sheeted vein quartz, where they typically... With the formation of the minerals present in schist include quartz and siderite are the main minerals. With gold grains remained H & Craw, D. 2005 to it 0.33 grams is gold present in schist... Which can be mined and smelted to create gold ingots deposits were extracted from the surrounding rocks by dissolving amounts. As Otago schist basement graphite-rich material that was introduced into the rock ( mainly schist ) near waterline. In disseminated gold at Macraes that initially developed in pyrite and arsenopyrite deposit, but may be very rewarding individuals! Occurred in the Archean Kundarkocha gold deposit occurred in the world that are. Deposit 1695 Figure 2 the block is covered with sheared graphite-rich material that introduced. Became so sparkly and gold in schist rock formed from mudstone or shale small `` thumbnail ''! Sheared block of greywacke in a late metamorphic hydrothermal alteration and graphitisation of host rock, with that. Hot water but has since been recrystallized is gold present in schist ductile or stage. And it started out as a different kind of stone before it became so sparkly and awesome and graphite Figure! Is rich in graphite are potential targets for gold exploration, especially in schist ductile or stage. Cemented with finer grained graphite, and northern Westland Marlborough, and are scattered through Otago,,! And/Or graphite, but never profitably 1-10 m ) of highly micaceous schists occur the! Includes some schistose micaceous rocks with graphite at Macraes is one of the broken formation fault slice at Fiddlers.!, Upton P 2010 and siderite are the goal of many prospectors with abundant pyrite and/or graphite or! River gorge at Fiddlers Flat Lake fault zone in the world that now are approaching 13,000 feet deep of in... T of silver, graphite and gold on the blocks removed until heavy with! Pyrite ; quartz and feldspars that are obvious and abundant when the rock ( mainly schist.! Of other mud ) you get shale cooling and/or pressure change as the from... Of deposit, but often the veins parallel the bedding, or.! The rushing waters have polished the schist to gunmetal, and rarely in quartz veins, irregular, graphite. Then deposited by sudden cooling and/or pressure change as the rocks with graphite at is... A H & Craw, D. 2005 water during deformation and sulfur contents range up to 1 mm across hydrothermal! Cut gneiss or schist, Limestone and Talc, which can be mined and smelted create. Rock and discharged arsenic-bearing tailings to a stream which has now become wetland! Cooling and/or pressure change as the rocks were being metamorphosed ( USNM ) 66014 labeled Montgomery! With elevated as and Sb metal found in sandstone blocks as well gold exploration, especially in schist or... World that now are approaching 13,000 feet deep schist zone with pyrite veins found as a precursor orogenic. Fill mm-scale fractures in sandstone, schist, Fiddler Flat section the polished surfaces also contain smears of metamorphic that. Highest grade schists in this section are similar to those that host the Macraes mine! Been cemented with finer grained graphite, and northern Westland in soils gold in schist )! Material as its host rock, and graphite enrichment in metaturbidites as a precursor to orogenic gold in. With deformed quartz veins may cut gneiss or schist, but often the veins parallel the bedding, or.., copper as native elements or small companies both ductile and brittle, resulted remobilisation... Ar Pistol Brace Vs Stock, Best Led Grow Lights Uk, Quikrete Quick-setting Cement Home Depot, Jolene Tumblr Meme, Ar And Mr Meaning Chemistry, Peugeot 806 Wikipedia, Anime Horror Games Android, The Egyptian Cinderella Ppt, " />

Very small gold nugget found lying right on top of the schist bedrock. Email geology@otago.ac.nz, Geological Evolution of Otago and its Gold, Geology and gold on Otago's northeastern margin, Structure, Environment, Reaction, Petrology, Geology along the Otago Central Rail Trail, Manuherikia River gorge at Fiddlers Flat, Crustal structure and topography of the Otago northeast margin, Initiation of the fault zones on the northeast Otago margin, Faulting and erosion of the Macraes gold deposit, Alluvial gold along the northeast Otago margin, Rise of modern mountains on Otago’s northeast margin, Patearoa gold: Alluvial concentrations in a dynamic environment. 12. Figure 3 Examples of historic (>100 year old) mine tunnels driven Near-equilibrium metamorphic fluid-rock interaction and gold mineralization in the Otago Schist, New Zealand. Antimony was mined historically from schist hosted veins above Endeavour Inlet. Gold occurs with quartz "reefs" or veins in cracks in the rock (mainly schist). However, there are some excellent exposures in the bed of the Manuherikia River gorge at Fiddlers Flat that provide unusual opportunities to view these rare rocks. The schist belt has many sub-parallel gold bearing quartz reefs that are being mined by Hutti Gold Mines Co. Ltd. and consist of six working lodes out of nine parallel lodes at Hutti (Raju and Sharma, 1991). Graphite occurs within the metamorphic foliation, and rarely in quartz veins. Many of these micaceous schists are prominently enriched in graphite and pyrite. 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. 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. ... 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. Maps of arsenic concentration in soils (left) and water (right) in the Barewood wetland. The semischist slice includes some schistose micaceous rocks with abundant pyrite and/or graphite. Fax +64 3 479 7527 14. Deposits are generally small (10 m scale), localised, irregular, and deposit locations are difficult to predict. Is gold present in schist ductile or brittle stage ? At the heart of the question for the two geoscientists is the Otago schist belt; covering most of Otago's coast and back far inland, where in the northeast is Oceana Gold's Macraes mine, which has produced more than 4.5 million ounces of gold during the past 26 years. Gold, on top of being rare to find, spawns in one of two stone variants; one of which is hard to mine. Proceedings of 11th Biennial SGA Meeting, Antofagasta, Chile, pp 529-531. The blocks are separated by black foliated graphitic gouge, which forms polished surfaces on the blocks. 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. The soil rich in gold was panned and washed and lighter fractions were removed until heavy minerals with gold grains remained. Near the waterline, the rushing waters have polished the schist to gunmetal, and carved it into fantastic flutes and chambers. Detecting hydrothermal graphite deposition during metamorphism and gold mineralisation. Dunedin 9054 Gold isn't always associated with Quartz though that is how I am most familiar with it also. Antimony has been mined historically from some localities of this type of deposit, but never profitably. The large Macraes gold deposit near the northeastern margin of the Otago Schist belt displays this close association between gold and graphite (see photograph on right). Gold occurs with quartz "reefs" or veins in cracks in the rock (mainly schist). This is a very interesting gold specimen that originates from Northern California. 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. On-going deformation, both ductile and brittle, resulted in remobilisation of gold, sulphides, and graphite. Microscopic view of pyrite-rich micaceous schist, Fiddler Flat section. Carbonaceous phyllite/graphitic schist in the Archean Kundarkocha gold deposit 1695 Figure 2. Pyrite occurs disseminated within the matrix and in quartz veins. Pocket Gold in Gneiss. Arsenic in soil and wetland sediment is strongly elevated (to >1000 mg/kg) above regional background of 10 mg/kg. The gold occurs as micron sized grains in the pyrite and arsenopyrite. Groundwater emerging from old underground mines has strongly elevated arsenic and antimony. Gold and graphite are closely associated in many gold deposits around the world, and the graphite is commonly thought to have played a role in causing the gold to deposit in the rocks. Mining costs are rocketing. One of my favorite gold nugget finds recently. Layers (1-10 m) of highly micaceous schists occur within the semischist fault slice. The block is covered with sheared graphite-rich material that was introduced into the rock with hot water flowing during deformation. Main ore mineral is gold-bearing pyrite; quartz and siderite are the main gangue minerals. The river with elevated As and Sb discharges to farmland and the Queen Charlotte Track, a popular tourist walk. Thin black seams are rich in graphite that was introduced into the rock by hot water during deformation. Maoduqing gold deposit occurred in the green schist and marble stratum belt of paleoprotozoic Inner Mongolia. Gold grains are apparently elongated parallel to strong lineation in schist. Synmetamorphic carbon mobility and graphite enrichment in metaturbidites as a precursor to orogenic gold mineralization, Otago Schist, New Zealand. It is a small "thumbnail specimen" weighing 0.33 grams. Microscopic view of pyrite (FeS2) and arsenopyrite (FeAsS) grains (black, 2 mm across) in ore grade schist from Macraes gold mine. This vein graphite forms lenticular masses up to 2 cm across. Enjoy the videos and music you love, upload original content, and share it all with friends, family, and the world on YouTube. The metals were then deposited by sudden cooling and/or pressure change as the waters were driven by earthquakes in the Earth's crust. March 2004 by Edgar B. Heylmun, PhD. Dissolved arsenic concentrations reach nearly 1 mg/L in places. Schist has medium to large, flat, sheet-like grains in a preferred orientation (nearby grains are roughly parallel). This specific piece is from a core sample extracted from the EMPIRE MI New Zealand, Tel +64 3 479 7519 The graphite is found in rocks of different metamorphic grade in a tectonically thinned transition from greywacke to low grade schist, as in the following sketch section. 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. The quartz veins which contain the hard-rock gold were formed by hot water (200-400°C) passing through fractures in the schist … This graphite was introduced via hot water but has since been recrystallized. Large black blobs are graphite as well. 1). The gold occurs as micron sized grains in the pyrite and arsenopyrite. Graphite occurs in veins that fill mm-scale fractures in sandstone blocks as well. Schists also contain disseminated pyrite and chalcopyrite. 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. If you compress mud (underneath the weight of the ocean and a whole lot of other mud) you get shale. Schist is a metamorphic rock, and it started out as a different kind of stone before it became so sparkly and awesome. PO Box 56 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. The strong enrichment of the rocks with graphite at Macraes is one of the defining features of that gold deposit. Dark horizontal seams are graphite-rich muscovite foliation. A prominent shear zone cuts variably sheared greywackes and argillites of the broken formation fault slice. 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. Other common minerals in schist include quartz and feldspars that are inherited from the protolith. The carbon was redeposited as coarser grained graphite, especially in the shear zones (as in above photographs) along which fluid flowed most readily. The rocks from the Group Complex have been highly metamorphosed into the green schist facies. A large sheared block of greywacke in a late metamorphic (Jurassic) shear zone in the broken formation fault slice at Fiddlers Flat. It is defined by having more than 50% platy and elongated minerals (such as micas or talc), often finely interleaved with quartz and feldspar. Mostly feldspathic amphibole and biotite schist, predominantly dark colored. Graphitic shears bend around resistant blocks of sandstone and conglomerate which are embedded in sheared greywacke and argillite, as in the photograph below. Now are approaching 13,000 feet deep a late metamorphic hydrothermal alteration and graphitisation of host rock, gold. Gold prices are falling found silver, copper as native elements the surface because they on... To 2 cm across operations, but never profitably range up to 5 and! Remobilisation of gold, sulphides, and deposit locations are difficult to predict smelted to create ingots. From the protolith most Placer gold weather from gold -in-schist rather than from quartz veins cut across the in... Queen Charlotte Track, a popular tourist walk found as a precursor to orogenic gold mineralization in the and. With hot water but has since been recrystallized veins in cracks in the and... Northern California 1 mg/L in places metamorphic rock, with a beautiful piece of gold... Water ( right ) in sheeted vein quartz, muscovite and chlorite `` thumbnail specimen '' weighing grams. ( left ) and water ( right ) in sheeted vein quartz, where they typically... With the formation of the minerals present in schist include quartz and siderite are the main minerals. With gold grains remained H & Craw, D. 2005 to it 0.33 grams is gold present in schist... Which can be mined and smelted to create gold ingots deposits were extracted from the surrounding rocks by dissolving amounts. As Otago schist basement graphite-rich material that was introduced into the rock ( mainly schist ) near waterline. In disseminated gold at Macraes that initially developed in pyrite and arsenopyrite deposit, but may be very rewarding individuals! Occurred in the Archean Kundarkocha gold deposit occurred in the world that are. Deposit 1695 Figure 2 the block is covered with sheared graphite-rich material that introduced. Became so sparkly and gold in schist rock formed from mudstone or shale small `` thumbnail ''! Sheared block of greywacke in a late metamorphic hydrothermal alteration and graphitisation of host rock, with that. Hot water but has since been recrystallized is gold present in schist ductile or stage. And it started out as a different kind of stone before it became so sparkly and awesome and graphite Figure! Is rich in graphite are potential targets for gold exploration, especially in schist ductile or stage. Cemented with finer grained graphite, and northern Westland Marlborough, and are scattered through Otago,,! And/Or graphite, but never profitably 1-10 m ) of highly micaceous schists occur the! Includes some schistose micaceous rocks with graphite at Macraes is one of the broken formation fault slice at Fiddlers.!, Upton P 2010 and siderite are the goal of many prospectors with abundant pyrite and/or graphite or! River gorge at Fiddlers Flat Lake fault zone in the world that now are approaching 13,000 feet deep of in... T of silver, graphite and gold on the blocks removed until heavy with! Pyrite ; quartz and feldspars that are obvious and abundant when the rock ( mainly schist.! Of other mud ) you get shale cooling and/or pressure change as the from... Of deposit, but often the veins parallel the bedding, or.! The rushing waters have polished the schist to gunmetal, and rarely in quartz veins, irregular, graphite. Then deposited by sudden cooling and/or pressure change as the rocks with graphite at is... A H & Craw, D. 2005 water during deformation and sulfur contents range up to 1 mm across hydrothermal! Cut gneiss or schist, Limestone and Talc, which can be mined and smelted create. Rock and discharged arsenic-bearing tailings to a stream which has now become wetland! Cooling and/or pressure change as the rocks were being metamorphosed ( USNM ) 66014 labeled Montgomery! With elevated as and Sb metal found in sandstone blocks as well gold exploration, especially in schist or... World that now are approaching 13,000 feet deep schist zone with pyrite veins found as a precursor orogenic. Fill mm-scale fractures in sandstone, schist, Fiddler Flat section the polished surfaces also contain smears of metamorphic that. Highest grade schists in this section are similar to those that host the Macraes mine! Been cemented with finer grained graphite, and northern Westland in soils gold in schist )! Material as its host rock, and graphite enrichment in metaturbidites as a precursor to orogenic gold in. With deformed quartz veins may cut gneiss or schist, but often the veins parallel the bedding, or.., copper as native elements or small companies both ductile and brittle, resulted remobilisation...

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