Native minerals

Silver occurs both as native ore and in combination with various silver sullide minerals. Native silvct is predominantly a product of primary deposition from hydrothermal solutions. Minor occurrences are products of oxidation of silver sullide minerals with which the native ore is seenndarily associated, Sec also Silver. 

Some metals occur in nature in an elemental state, and as such are minerals (native elements). Most metals, however, are stable only when in combination with at least one other element. 

Many less common elements (e.g. Ga and Ge) are incorporated to some extent into the crystal structures of major minerals, and thus may be rather thinly spread over the crust. Others are concentrated by forming individual minerals. Native gold and cinnabar (HgS) were known in antiquity although Au and Hg are very rare elements. On the other hand, the less rare Ga and Ge were not discovered until the late 19th century. 

Most Important mineral Native sulfur S is found near volcanoes and hot springs (Figure M73) Pyrite FeS (Figure M74)... 

It is not abundant, but is found in over 100 mineral species. It is sometimes found native, but more frequently as the sulfide stibnite. 

Copper occasionally occurs native, and is found in many minerals such as cuprite, malachite, azurite, chalcopyrite, and bornite. 

L. Holmia, for Stockholm). The special absorption bands of holmium were noticed in 1878 by the Swiss chemists Delafontaine and Soret, who announced the existence of an "Element X." Cleve, of Sweden, later independently discovered the element while working on erbia earth. The element is named after cleve s native city. Holmia, the yellow oxide, was prepared by Homberg in 1911. Holmium occurs in gadolinite, monazite, and in other rare-earth minerals. It is commercially obtained from monazite, occurring in that mineral to the extent of about 0.05%. It has been isolated by the reduction of its anhydrous chloride or fluoride with calcium metal. 

Nonsulfide Ore Flotation. Nonsulfide minerals recovered by flotation include native elements such as graphite, diamonds, copper, gold, and numerous oxides as well as salts such as carbonates, phosphates, tungstates, and the like. Examples of value-bearing nonsulfide, noncoal minerals include... 

Sulfur constitutes about 0.052 wt % of the earth s cmst. The forms in which it is ordinarily found include elemental or native sulfur in unconsohdated volcanic rocks, in anhydrite over salt-dome stmctures, and in bedded anhydrite or gypsum evaporate basin formations combined sulfur in metal sulfide ores and mineral sulfates hydrogen sulfide in natural gas organic sulfur compounds in petroleum and tar sands and a combination of both pyritic and organic sulfur compounds in coal (qv). 

Copper ore minerals maybe classified as primary, secondary, oxidized, and native copper. Primaryrninerals were concentrated in ore bodies by hydrothermal processes secondary minerals formed when copper sulfide deposits exposed at the surface were leached by weathering and groundwater, and the copper reprecipitated near the water table (see Metallurgy, extractive). The important copper minerals are Hsted in Table 1. Of the sulfide ores, bornite, chalcopyrite, and tetrahedrite—teimantite are primary minerals and coveUite, chalcocite, and digenite are more commonly secondary minerals. The oxide minerals, such as chrysocoUa, malachite, and azurite, were formed by oxidation of surface sulfides. Native copper is usually found in the oxidized zone. However, the principal native copper deposits in Michigan are considered primary (5). 

Berg-kalk, m. rock time (Geol.) mountain limestone. -kiesel, m. rock flint, chert felsite. -kohle,/. (mineral) coal, -kork, m. mountain cork (a light form of asbestos), -kreide, /. rock lime, -kristall, -krystall, m. rock crystal (transparent quartz), -kupfer, n. native copper, -lasur, /. azurite. -leder, n. mountain leather (a form of asbestos), -maun, m miner. 

This element occurs in nature in the uncombined state as native copper and in the combined state as various oxides, sulfides, and carbonates. The chief mineral is chalcopyrite, CuFeS2, from which the element is extracted by roasting (heating in air) followed by reduction. The roasting reaction can be written... 

Ozocarite or Ozokerite (Mineral Wax, Fossil Wax, Native Paraffin), In purified form known as Ceresine Wax (see under Waxes). Waxlike hydrocarbon mixt, yel brown to black or green, translucent when pure and having a greasy feel. D 0.85—0.95g/cc, mp 55—... 

The eleetronic configuration of the group-IIA elements, [inert gas] ns, render them so reactive that they never occur native but are always combined with other elements. Thus, Be is found in complex silicate minerals Mg, Ca, Sr and Ba, however, occur in carbonate, sulfate or phosphate ores. Consequently, whereas the extractive metallurgy of Be is relatively complex, that for the other elements is quite straightforward. 

Ash and minerals (Ca, Na, K and Mg++) content was determined in AIS of fresh as well as canned carrots (Table 3). The native Ca " bound in the ceU wall components of fresh carrots was found to be 10.9 mg/g AIS. In the presence of CaClz the conventionally canned carrots showed a sharp increase in Ca ... 

Native silver is found in bornite-rich black ore (Matsukuma and Yui, 1979 Matsukuma, 1985) and it is thought to be secondary mineral. 

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