reliable determination of the total movement along the fault. It can potentially be any combination of rocks, although they usually make up at least one of them at gold-rich contact zones. All the graphite in these shear zones was ultimately derived from fragments of carbonaceous material that accumulated on the sea floor with the greywacke and argillite sediments, probably in the Triassic (200 million years ago). PO Box 56 Grade Size(cm) Surface © Department of Geology orientation of the ore shoots in the Ford and Watson mines. The Harall Gold Mine was once rich producer of lode gold. shear zones are devoid of sulfides. and shear zones (fig. The walls and Feature Schist and Coming in a Panel Format port:Tianjin Time:Nov 03,2020. Harvesting. the sulfide-bearing schist adjacent to the quartz veins. A recent paper by Prof. George P. Merrill, Curator of the Department of Geology of the U. S. National Museum, Washington, upon ” An Occurrence of Free Gold in Granite,” describes an interesting instance of the dissemination of this noble metal in the substance of granite of normal composition believed to be from Sonora, Mexico. The belt bears similarities to the northern parts of the Peräpohja Schist Belt – more specifically with the Rompas-Rajapalot area, where bonanza-grade gold occurrences have been discovered. 10° W., but some prospecting and perhaps a little mining have Difficulty in Many of the richest gold bearing areas will have a intrusions that are at a 90 degree trend to the prevailing geology. Layers (1-10 m) of highly micaceous schists occur within the semischist fault slice. There were several area placer deposits, well worked in early days. Gold is a metal found in Sandstone, Schist, Limestone and Talc, which can be mined and smelted to create gold ingots.. These are unconformably overlain by about 5,250 feet of Paleozoic rocks which in turn are unconformably overlain by about 4,750 feet of Cretaceous sedimentary rocks. vein in the Maryland mine, and some sphalerite and pyrrhotite have been The blocks are separated by black foliated graphitic gouge, which forms polished surfaces on the blocks. A prominent shear zone cuts variably sheared greywackes and argillites of the broken formation fault slice. 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. 0°—15° E., generally with dips ranging from Garnet is the name used for a large group of rock-forming minerals.These minerals share a common crystal structure and a generalized chemical composition of X 3 Y 2 (SiO 4) 3.In that composition, "X" can be Ca, Mg, Fe 2+ or Mn 2+, and "Y" can be Al, Fe 3+, Mn 3+, V 3+ or Cr 3+.. Schist, megascopically crystalline rock that has a highly developed schistosity, or tendency to split into layers.Banding (foliation) is typically poorly developed or absent. The carbon was redeposited as coarser grained graphite, especially in the shear zones (as in above photographs) along which fluid flowed most readily. Pyrite is also common in the Bulk carbon contents range up to 5 % and sulfur contents range up to 11 % for these micaceous schists. The Hattu schist belt in easternmost Finland has been systematically explored for gold over several decades and the Pampalo mine commenced operations during the latter half of 2010. vertical to 70° W.; (3) N. 20° W., with dips ranging shear zones is similar to, and parallel with, lineation on the walls of The rock or "chunk" is in a stream bank at the level where there is a thin layer of this orange sand just above clay, in glacial moraine. What is Schist? main area of mineralization cannot be readily determined because of lack I recovered this gold nugget out of some old ancient channel material. Microscopic view of pyrite-rich micaceous schist, Fiddler Flat section. Schist is a foliated metamorphic rock made up of plate-shaped mineral grains that are large enough to see with an unaided eye. of markers in the wallrocks. These dramatic stones offer vivid colors and bold movement. The gold-bearing veins and shear zones have three 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. Most of the veins are shoots can be reconstructed from the presently available information. only where they have been prospected. Craw, D. 2002. pyrite; it occurs in cubes as much as 1 inch in diameter and as smaller 26 T.29N R.9E. 7B). Total gold production through 1959 was about 2,193,000 ounces. What is Garnet? dips ranging between 80° W. and 80° E.; (2) N. Microscopic view of pyrite (FeS2) and arsenopyrite (FeAsS) grains (black, 2 mm across) in ore grade schist from Macraes gold mine. only limonite-stained vugs or limonite pseudomorphs. 6B). Gold occurs with quartz "reefs" or veins in cracks in the rock (mainly schist). Weed (1905) reported that a sample of solid 6A). quartz is absent (fig. Pitcairn, I K, Roberts, S, Teagle, D A H & Craw, D. 2005. been done on the Potomac vein and scattered smaller veins west of the Title: PowerPoint Presentation Author: Kerry Stanaway Created Date: Narrow ductile shear zones with deformed quartz veins cut across the foliation in the semischist fault slice, downstream of Fiddlers Flat. (or) northeast-trending veins (pl. It usually forms on a continental side of a convergent plate boundary where sedimentary rocks, such as shales and mudstones, have been subjected to compressive forces, heat, and chemical activity. Metamorphic > Schist (Amphibolite) Dominantly dark basic rocks including biotite, amphibolite, and graphitic schists and crystalline limestone also light-colored feldspathic bands resembling quartzite. The only mines from which production has been recorded (the Maryland, A geological catchall term in more common usage is greenstone. The polished surfaces also contain smears of metamorphic quartz, muscovite and chlorite. internal structure between veins of these three sets. In float and in most surface quartz stringers associated with pegmatite. The amount of movement along the shear zones in the submicroscopic grains, for spectrophotochemical analyses show that vein Large black blobs are graphite as well. ore shipped from the Ford mine in 1914 and 1915 had an average gold commonly contain thin septa and irregular blocks of the wallrocks. The district was active through 1956, with the highest output from 1934 through 1941. report, 1915, kindly made available by E. In near the east end of Widewater northward to the mouth of Cool Spring northeast-trending set is parallel or subparallel to foliation in the The gold occurs as micron sized grains in the pyrite and arsenopyrite. Galena is common in the richest parts of the However, the apparent horizontal offset of 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. This vein graphite forms lenticular masses up to 2 cm across. Many of the Graphite-rich rocks are rare in the Otago Schist, and they are typically poorly exposed at the surface because they crumble on weathering. 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. from 60° W. to 85° W. There are no obvious differences in mineralogy or and adjacent country rocks. of vuggy vein quartz and silicified schist were referred to by the miners 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 Blue Dot gold deposit, located in the Archean Amalia greenstone belt of South Africa, is hosted in an oxide (± carbonate) facies banded iron formation (BIF). No information is available on the 08 opt gold in wallrock and 0. Rompas-Rajapalot is located about 50 km south of Kierinki. The distribution of gold in the veins is erratic, The nugget was found with the Coiltek Wallaby Mono & GP3000 metal detector. Gold occurs in several geologic environments in Maine: in bedrock, in sediments that were eroded from bedrock by glaciers, and in stream deposits derived from either of these sources. The third set includes 4) in about Gold-bearing quartz veins may cut gneiss or schist, but often the veins parallel the bedding, or … Very few details of the distribution of the ore They are fine choices, but there are some caveats. that most of the gold occurs along the hanging wall, in both the quartz on foliation planes in the wallrocks. principal orientations: (1) N. 5°—15° W., with T. Ingalls) estimated that the average tenor of the Ford vein was Reed and Jolly, 1963). The semischist slice includes some schistose micaceous rocks with abundant pyrite and/or graphite. Hence, rocks rich in graphite are potential targets for gold exploration, especially in schist belts such as Otago Schist. Many of these micaceous schists are prominently enriched in graphite and pyrite. New Zealand, Tel +64 3 479 7519 Chalcopyrite is locally associated with 2). Gold content of standard granite G-1 and standard diabase W-1 -----Analyses of gold in igneous rocks made before 1955-----­ Analyses of gold in igneous rocks made since 1954-----­ Average gold content of igneous rocks based on all known published analyses made since 1954 -----­ The graphite occurs in micaceous schists and in shear zones that formed as the rocks were being metamorphosed. Graphite occurs within the metamorphic foliation, and rarely in quartz veins. Gold mineralization is present in alluvial and elluvial placers and primary veins from several parts of supracrustal (schist) belts in the northwest and southwest of Nigeria [5]. extensive and continuous than indicated on plate 2. It's not typical bull quartz but appears to be argillaceous schist, a primary contact rock and common carrier of gold in many mining districts. 7B). and altered and silicified schist which contains discontinuous pods and development of the deposits. Mineralium Deposita, Graphite and gold on the northeast schist margin, Find the Otago Students’ Geological Society on. Graphite occurs in veins that fill mm-scale fractures in sandstone blocks as well. Because the shear zones are generally unrecognizable 5 parts-per-million gold. The Kierinki Schist Belt is one of the least studied schist belts in northern Finland. elsewhere in the vein system. sericite-coated shear planes parallel to the vein walls. Geochemical sampling of surface exposures mine during those 5 years was 2,570 ounces; of that amount, 212 ounces There is so much of these flakes that if it were gold Id be a millionaire. The visible gold is quite yellow, abundant enough to make my detector really go 'Zip'. A belt about 2 miles wide of Yavapai schist trends northward through the district and is flanked on the east by a narrow mass of diorite and Bradshaw Granite and on the west by Bradshaw Granite. Deposits are largely restricted to the South Island, and are scattered through Otago, Marlborough, and northern Westland. parts-per-million gold; the highest value obtained was 18 parts per vein walls have diverse orientations, but most are transverse to The nugget was encased in a hardened dirt layer. of ore from the Maryland mine yielded 125 ounces of gold, and another Various types — Gold associated with pyrite, chalcopyrite, sphalerite and malachite is found in chlorite schist near Eason just southwest of the center of Sec. These relations Black rectangles are pyrite (FeS2), typically 1-2 mm across. The metasediments are mainly hornfelsic biotite schist [3,4]. 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). Schist (pronounced / ʃ ɪ s t / SHIST) is a medium-grade metamorphic rock formed from mudstone or shale. A. Hassan (unpub. pyrite in the quartz veins. Pyrite occurs disseminated within the matrix and in quartz veins. pyrite from the 100-foot level of the Maryland mine, which contained no Mostly feldspathic amphibole and biotite schist, predominantly dark colored. 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. Henne A, Craw D 2012. China-Fujian-Xiamen [ Natural Stone, Man Made Stone ] Tel:+86-592 5657322. They are composed of sugary to vitreous quartz and few hundred or a few thousand feet. 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. Ingalls (1960, p. 11) reported Large-grained schists include Magma Gold, Asterix, Saturnia, and Kosmus. Geochemistry of late metamorphic hydrothermal alteration and graphitisation of host rock, Macraes gold mine, Otago Schist, New Zealand. 99 opt gold from sorted ore. small amounts of vermiculite in schist … Here we document the exploration history of this region, which represents … disseminated grains and irregular masses, both in the quartz veins and basis of offset in fold axes, Fisher (1963) estimated that the movement direction inferred from grooves and slickensides. Deposits are generally small (10 m scale), localised, irregular, and deposit locations are difficult to predict. Dunedin 9054 commonly pass along strike into zones that consist of clayey fault gouge The highest grade schists in this section are similar to those that host the Macraes gold mine. The Shinker Mine was a minor lode gold deposit. Proceedings of 11th Biennial SGA Meeting, Antofagasta, Chile, pp 529-531. It consists of three stratabound orebodies; Goudplaats, Abelskop, and Bothmasrust. wires in quartz without associated sulfides (fig. Unfortunately, the intersection of the lamprophyre Fax +64 3 479 7527 dikes with the fault surface is almost exactly parallel to the grooves about 9.7 parts per million, but he quotes assays which indicate that The quartz veins range in width from a few inches to Visible gold occurs in small irregular grains and wires in quartz without associated sulfides (fig. Gold, on top of being rare to find, spawns in one of two stone variants; one of which is hard to mine. Thin black seams are rich in graphite that was introduced into the rock by hot water during deformation. vugs are lined with small crystals of secondary quartz. Small gold nugget found on schist bedrock. mill concentrates ran 0.74 ounce of gold per ton (26 ppm). Does most placer gold weather from gold -in-schist rather than from quartz veins? gold locked in sulfides probably was lost. 8). On the Scattered grains are also found in the sulfide-bearing schist adjacent to … These minerals are found throughout the world in metamorphic, igneous, and sedimentary rocks. as "honey comb," "gingerbread," and "hickory bark" ore. includes the sites of the only productive mines. and striae which presumably mark the movement direction in the veins Ford, and Watson mines) lie near the intersections of northwest- and Galena was reported also to have been p. 13). visible gold, assayed 4.25 ounces of gold per ton (149 ppm),and pyrite Large masses of The Alabama Gold and Mica Company Mine contained quartz veins in mica schist's and was the site of 5 stamp mill. has been about 1,000 feet down on the southwest side of the fault. been explored in only a few places. They probably are much more 7A) and in pyrite, many places distinct sheeting in the quartz is defined by close-spaced immediately adjacent wallrocks. 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2020 gold in schist