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Ore is natural rock or sediment that contains one or more valuable minerals, typically including metals, concentrated above background levels, and that is economically viable to mine and process. The grade of ore refers to the concentration of the desired material it contains. The value of the metals or minerals a rock contains must be weighed against the cost of extraction to determine whether it is of sufficiently high grade to be worth mining and is therefore considered an ore. A complex ore is one containing more than one valuable mineral.
In geology, a lode is a deposit of metalliferous ore that fills or is embedded in a fracture in a rock formation or a vein of ore that is deposited or embedded between layers of rock. The current meaning dates from the 17th century, being an expansion of an earlier sense of a "channel, watercourse" in Late Middle English, which in turn is from the 11th-century meaning of lode as a "course, way".
Austin is an unincorporated small town in, and former county seat of, Lander County, Nevada, United States. In 2020, the census-designated place of Austin had a population of 167. It is located on the western slopes of the Toiyabe Range at an elevation of 6,575 feet (2,004 m). U.S. Route 50 passes through the town.
Volcanogenic massive sulfide ore deposits, also known as VMS ore deposits, are a type of metal sulfide ore deposit, mainly copper-zinc which are associated with and produced by volcanic-associated hydrothermal vents in submarine environments.
Greisen is a highly altered granitic rock or pegmatite, usually composed predominantly of quartz and micas. Greisen is formed by self-generated alteration of a granite and is a class of moderate- to high-temperature magmatic-hydrothermal alteration related to the late-stage release of volatiles dissolved in a magma during the solidification of that magma.
Porphyry copper deposits are copper ore bodies that are formed from hydrothermal fluids that originate from a voluminous magma chamber several kilometers below the deposit itself. Predating or associated with those fluids are vertical dikes of porphyritic intrusive rocks from which this deposit type derives its name. In later stages, circulating meteoric fluids may interact with the magmatic fluids. Successive envelopes of hydrothermal alteration typically enclose a core of disseminated ore minerals in often stockwork-forming hairline fractures and veins. Because of their large volume, porphyry orebodies can be economic from copper concentrations as low as 0.15% copper and can have economic amounts of by-products such as molybdenum, silver, and gold. In some mines, those metals are the main product.
Various theories of ore genesis explain how the various types of mineral deposits form within Earth's crust. Ore-genesis theories vary depending on the mineral or commodity examined.
In geology, a vein is a distinct sheetlike body of crystallized minerals within a rock. Veins form when mineral constituents carried by an aqueous solution within the rock mass are deposited through precipitation. The hydraulic flow involved is usually due to hydrothermal circulation.
Sedimentary exhalative deposits are zinc-lead deposits originally interpreted to have been formed by discharge of metal-bearing basinal fluids onto the seafloor resulting in the precipitation of mainly stratiform ore, often with thin laminations of sulfide minerals. SEDEX deposits are hosted largely by clastic rocks deposited in intracontinental rifts or failed rift basins and passive continental margins. Since these ore deposits frequently form massive sulfide lenses, they are also named sediment-hosted massive sulfide (SHMS) deposits, as opposed to volcanic-hosted massive sulfide (VHMS) deposits. The sedimentary appearance of the thin laminations led to early interpretations that the deposits formed exclusively or mainly by exhalative processes onto the seafloor, hence the term SEDEX. However, recent study of numerous deposits indicates that shallow subsurface replacement is also an important process, in several deposits the predominant one, with only local if any exhalations onto the seafloor. For this reason, some authors prefer the term clastic-dominated zinc-lead deposits. As used today, therefore, the term SEDEX is not to be taken to mean that hydrothermal fluids actually vented into the overlying water column, although this may have occurred in some cases.
Silver mining is the extraction of silver by mining. Silver is a precious metal and holds high economic value. Because silver is often found in intimate combination with other metals, its extraction requires the use of complex technologies. In 2008, approximately 25,900 metric tons of silver were consumed worldwide, most of which came from mining. Silver mining has a variety of effects on the environment, humans, and animals.
A polymetallic replacement deposit, also known as carbonate replacement deposit or high-temperature carbonate-hosted Ag-Pb-Zn deposit, is an orebody of metallic minerals formed by the replacement of sedimentary, usually carbonate rock, by metal-bearing solutions in the vicinity of igneous intrusions. When the ore forms a blanketlike body along the bedding plane of the rock, it is commonly called a manto ore deposit. Other ore geometries are chimneys and veins. Polymetallic replacements/mantos are often stratiform wall-rock replacement orebodies distal to porphyry copper deposits, or porphyry molybdenum deposits. The term manto is derived from the Spanish word manto, meaning "mantle" or "cloak".
Roscoelite is a green mineral from the mica group that contains vanadium.
Silver mining in Nevada, a state of the United States, began in 1858 with the discovery of the Comstock Lode, the first major silver-mining district in the United States. Nevada calls itself the "Silver State." Nevada is the nation's second-largest producer of silver, after Alaska. In 2014 Nevada produced 10.93 million troy ounces of silver, of which 6.74 million ounces were as a byproduct of the mining of gold. The largest byproducers were the Hycroft Mine, the Phoenix Mine, the Midas Mine and Round Mountain.
Gold mining in Nevada, a state of the United States, is a major industry, and one of the largest sources of gold in the world. In 2018 Nevada produced 5,581,160 troy ounces, representing 78% of US gold and 5.0% of the world's production. Total gold production recorded from Nevada from 1835 to 2017 totals 205,931,000 troy ounces (6,405.2 t), worth US$322.6 billion at 2020 values. Much of Nevada's gold production comes from large open pit mining using heap leaching recovery.
Wonder, Nevada, is a ghost town in Churchill County, Nevada, approximately 39 miles (63 km) east of Fallon.
The Admiralty mining district is a mining area in the U.S. state of Alaska which consists of Admiralty Island. Silver and base metals are mined, with gold recovered as a by-product.
Coneto de Comonfort is a town and seat of the municipality of Coneto de Comonfort, in the state of Durango, north-western Mexico. As of 2015, the town of Coneto de Comonfort had a population of 858. The town has many desposits of quartz and stone.
Carlin–type gold deposits are sediment-hosted disseminated gold deposits. These deposits are characterized by invisible gold in arsenic rich pyrite and arsenopyrite. This dissolved kind of gold is called "invisible gold", as it can only be found through chemical analysis. The deposit is named after the Carlin mine, the first large deposit of this type discovered in the Carlin Trend, Nevada.
Hydrothermal mineral deposits are accumulations of valuable minerals which formed from hot waters circulating in Earth's crust through fractures. They eventually produce metallic-rich fluids concentrated in a selected volume of rock, which become supersaturated and then precipitate ore minerals. In some occurrences, minerals can be extracted for a profit by mining. Discovery of mineral deposits consumes considerable time and resources and only about one in every one thousand prospects explored by companies are eventually developed into a mine. A mineral deposit is any geologically significant concentration of an economically useful rock or mineral present in a specified area. The presence of a known but unexploited mineral deposit implies a lack of evidence for profitable extraction.
An orogenic gold deposit is a type of hydrothermal mineral deposit. More than 75% of the gold recovered by humans through history belongs to the class of orogenic gold deposits. Rock structure is the primary control of orogenic gold mineralization at all scales, as it controls both the transport and deposition processes of the mineralized fluids, creating structural pathways of high permeability and focusing deposition to structurally controlled locations.
References
- ↑ John, David A.; Vikre, Peter G.; Du Bray, Edward A.; Blakely, Richard J.; Fey, David L.; Rockwell, Barnaby W.; Mauk, Jeffrey L.; Anderson, Eric D.; Graybeal, Frederick T. (2018). "Descriptive models for epithermal gold-silver deposits". Scientific Investigations Report. doi:10.3133/sir20105070Q.
- ↑ MAT, Mahmut (2023-02-17). "Vein deposits » Geology Science". Geology Science. Retrieved 2024-02-06.
- ↑ Tilley, David (2021-08-13). "Epithermal Gold Deposits | Geology for Investors". www.geologyforinvestors.com. Retrieved 2024-02-06.
- ↑ "(PDF) High Sulfidation Au(-Ag-Cu) Deposits in Indonesia: A Review".
- ↑ Tharalson, Erik R.; Monecke, Thomas; Reynolds, T. James; Zeeck, Lauren; Pfaff, Katharina; Kelly, Nigel M. (December 2019). "The Distribution of Precious Metals in High-Grade Banded Quartz Veins from Low-Sulfidation Epithermal Deposits: Constraints from µXRF Mapping". Minerals. 9 (12): 740. Bibcode:2019Mine....9..740T. doi: 10.3390/min9120740 . ISSN 2075-163X.
- ↑ "Japanese Gold Mining Rejuvenated by Low-sulfidation Epithermal Gold Systems | INN". investingnews.com. Retrieved 2024-02-06.
- ↑ "Low Sulphidation Epithermal Gold Deposits". 2015-07-23. Retrieved 2024-02-06.
- ↑ "Comstock Lode, Virginia City, Comstock Mining District, Storey County, Nevada, USA".
- ↑ Hudson, Donald M. (April 2003). "Epithermal Alteration and Mineralization in the Comstock District, Nevada". Economic Geology. 98 (2): 367–385. doi:10.2113/gsecongeo.98.2.367.
- ↑ Barker, Shaun L.L.; Hood, Shawn; Hughes, Rosie M.; Richards, Shannon (2019). "The lithogeochemical signatures of hydrothermal alteration in the Waihi epithermal district, New Zealand". New Zealand Journal of Geology and Geophysics. 62 (4): 513–530. Bibcode:2019NZJGG..62..513B. doi:10.1080/00288306.2019.1651345. S2CID 202899356.
- ↑ https://www.sec.gov/Archives/edgar/data/1300050/000127956917000328/v460375_ex99-1.htm
- ↑ "PorterGeo Database - Ore Deposit Description". portergeo.com.au. Retrieved 2024-02-07.