ore deposit

Although chromium occurs in many minerals, the only ore exploited commercially is chromite. This spinel mineral is ideally composed of ferrous oxide and chromic oxide with the chemical composition FeO · Cr₂O₃, but it is often found in nature with magnesia (MgO) substituting for…

Principal forms in which copper ores are found include native copper, porphyry copper, massive deposits, and mixed ores. Native copper is simply the metal found unadulterated in nature. Occasionally copper is still found in its native form, but more frequently it is mixed with…

The major ores of gold contain gold in its native form and are both exogenetic (formed at the Earth’s surface) and endogenetic (formed within the Earth). The best-known of the exogenetic ores is alluvial gold. Alluvial gold refers to gold found in riverbeds, streambeds,…

Iron ores occur in igneous, metamorphic (transformed), or sedimentary rocks in a variety of geologic environments. Most are sedimentary, but many have been changed by weathering, and so their precise origin is difficult to determine. The most widely distributed iron-bearing minerals are oxides, and…

Of the more than 60 known lead-containing minerals, by far the most important primary ore of the metal is the lead sulfide galena (PbS). Galena often contains silver, zinc, copper, cadmium, bismuth, arsenic, and antimony; in fact, the value of the silver content often…

Among the ore minerals, the most common are the carbonates dolomite (a compound of magnesium and calcium carbonates, MgCO₃·CaCO₃) and magnesite (magnesium carbonate, MgCO₃). Less common is the hydroxide mineral brucite, Mg(OH)₂, and the halide mineral carnallite (a compound of magnesium and potassium chlorides and water, MgCl₂

The most important manganese ores are the oxides pyrolusite, romanechite, manganite, and hausmannite and the carbonate ore rhodochrosite. Rhodonite and braunite, both silicate ores, are frequently found with the oxides. Only ores containing greater than 35 percent manganese are considered commercially exploitable. Impurities include…

There are more than 25 known minerals containing mercury, but the principal ore mineral is cinnabar, a soft, red to reddish brown mercury sulfide. Some cinnabar deposits may also contain elemental mercury. The mineral has been found in all continents except Antarctica. It occurs…

The only commercially viable mineral in the production of molybdenum is its bisulfide (MoS₂), found in molybdenite. Almost all ores are recovered from porphyry-disseminated deposits. These are either primary molybdenum deposits or complex copper-molybdenum deposits from which molybdenum is recovered as a coproduct or…

Canadian ores are sulfides containing nickel, copper, and iron. The most important nickel mineral is pentlandite, (Ni, Fe)₉S₈, followed by pyrrhotite, usually ranging from FeS to Fe₇S₈, in which some of

Niobium occurs mostly as an oxide and has a strong geochemical coherence with tantalum. Major minerals of niobium are pyrochlore [(Na, Ca)₂Nb₂O₆F] and columbite [(Fe, Mn)(Nb, Ta)₂O₆], consisting of niobate, tantalate, iron, and manganese. Pyrochlore occurs usually in carbonatites and in pegmatite derived from…

With the exception of small alluvial deposits of platinum, palladium, and iridosmine (an alloy of iridium and osmium), virtually no ores exist in which the major metal is from the platinum group. Platinum minerals are usually highly disseminated in sulfide ores, particularly the nickel…

Although some silver-bearing ores contain silver as their largest metal value, virtually none has silver as its main constituent. A typical ore might contain 0.085 percent silver, 0.5 percent lead, 0.5 percent copper, and 0.3 percent antimony. After flotation separation, the concentrate would contain…

The major commercial source of thorium is monazite, an anhydrous rare earth phosphate with the chemical formula (Ce,La,Nd,Th)PO₄. Typically, 3 to 5 percent of the metal content of monazite is thorium (in the form of thorium dioxide, ThO₂). Much of the world’s current demand…

The principal tin mineral is cassiterite, or tinstone (SnO₂), a naturally occurring oxide of tin containing about 78.8 percent tin. Of less importance are two complex sulfide minerals, stannite (Cu₂FeSnS₄), a copper-iron-tin sulfide, and cylindrite (PbSn₄FeSb₂S₁₄), a lead-tin-iron-antimony sulfide. These two

Titanium is the fourth most abundant structural metal on Earth, exceeded only by aluminum, iron, and magnesium. Workable mineral deposits are dispersed worldwide and include sites in Australia, the United States, Canada, South Africa, Sierra Leone, Ukraine

Major minerals of tungsten are essentially of two categories. The first is wolframite [(Fe, Mn)WO₄], which contains iron and manganese tungstates in all proportions between 20 and 80 percent of each. The second is scheelite (CaWO₄), which fluoresces a bright bluish colour under ultraviolet…

Uranium ores occur in deposits that are both near-surface and very deep (e.g., 300 to 1,200 meters, or 1,000 to 4,000 feet). The deep ores sometimes occur in seams as thick as 30 meters. As is the case with ores of other metals, surface uranium ores are readily mined…

The important vanadium minerals are patronite (VS₄), carnotite [K₂(UO₂)₂(VO₄)₂], and vanadinite, [Pb₅(VO₄)₃Cl]. Ore deposits mined solely for vanadium are rare because much of the vanadium in igneous rocks occurs in the relatively insoluble trivalent state, substituting for ferric iron in ferromagnesium silicates, magnetite (an…

Zinc ores are widely distributed throughout the world, although more than 40 percent of the world’s output originates in North America and Australia. The common zinc-containing minerals are the zinc sulfide known as zinc blende or sphalerite (ZnS), a ferrous form of zinc blende…