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High-grade gold ore from the Harvard Mine, Jamestown, California, a wide quartz-gold vein in California's Mother Lode. Specimen is 3.2 cm (1.3 in) wide. 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.
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Mineral resource estimation is used to determine and define the ore tonnage and grade of a geological deposit, from the developed block model.There are different estimation methods used for different scenarios dependent upon the ore boundaries, geological deposit geometry, grade variability and the amount of time and money available.
Iron ore (banded iron formation) Manganese ore – psilomelane (size: 6.7 × 5.8 × 5.1 cm) Lead ore – galena and anglesite (size: 4.8 × 4.0 × 3.0 cm). 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.
Bauxite (aluminium ore) Beckerite (natural resin) Bentonite (mixture of montmorillonite and other clays) Bixbite (red gem variety of beryl) Bowenite (variety of antigorite) Brammallite (variety of illite) Brokenhillite (not approved by IMA) Buergerite (renamed to fluor-buergerite) Bursaite (not approved by IMA) Bytownite (variety of anorthite)
The most commonly mined ore of copper, chalcopyrite, is itself a copper-iron-sulfide and occurs with a range of other sulfides. Thus, copper mines are often major culprits of acid mine drainage. At some mines, acidic drainage is detected within 2–5 years after mining begins, whereas at other mines, it is not detected for several decades.
Ore bodies of orogenic gold deposits are generally defined by ≤ 3–5% sulfide minerals, most commonly arsenopyrite in metasedimentary host rocks and pyrite/pyrrhotite in meta-igneous rocks, and ≤ 5–15% carbonate minerals, such as ankerite, dolomite and calcite. [16]
There are several classification systems for the economic evaluation of mineral deposits worldwide. The most commonly used schemes base on the International Reporting Template, [1] developed by the CRIRSCO - Committee for Mineral Reserves International Reporting Standards, like the Australian Joint Ore Reserves Committee - JORC Code 2012, [2] the Pan-European Reserves & Resources Reporting ...