Elements native

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 is widely distributed as sulfide ores, which include galena, PbS cinnabar, HgS iron pyrite, FeS, and sphalerite, ZnS (Fig. 15.11). Because these ores are so common, sulfur is a by-product of the extraction of a number of metals, especially copper. Sulfur is also found as deposits of the native element (called brimstone), which are formed by bacterial action on H,S. The low melting point of sulfur (115°C) is utilized in the Frasch process, in which superheated water is used to melt solid sulfur underground and compressed air pushes the resulting slurry to the surface. Sulfur is also commonly found in petroleum, and extracting it chemically has been made inexpensive and safe by the use of heterogeneous catalysts, particularly zeolites (see Section 13.14). One method used to remove sulfur in the form of H2S from petroleum and natural gas is the Claus process, in which some of the H2S is first oxidized to sulfur dioxide ... 

Sulfur for commercial purposes is derived mainly from native elemental sulfur mined by the Frasch process. Large quantities of sulfur are also recovered from the roasting of metal sulfides and the refining of crude oil, i.e., from the sulfur by-products of purified sour natural gas and petroleum (the designation sour is generally associated with high-sulfur petroleum products). Reserves of elemental sulfur in evaporite and volcanic deposits and of sulfur associated with natural gas,... 

Native elements, metals, semimetals, nonmetals Gold, silver, copper, arsenic, antimony, bismuth, copper, sulfur... 

There are two basic types of elements metals and nonmetals. The metals, such as copper, gold, and iron (see Chapter 5), make up more than three-quarters of the total number of elements nonmetals, such as, for example, chlorine, sulfur and carbon, make up much of the rest. Other elements, however, known as the metalloids or semimetals, have properties intermediary between the metals and the nonmetals (see Appendix I). Only a few elements, such as the metals gold and copper and the nonmetal sulfur, which are known as the native elements, occur in nature uncombined. Most elements occur naturally combined with others, forming compounds. It is from these compounds, which occur in the crust of the earth as minerals, rocks, or sediments, that humans extract most of the elements that they require (Klein 2000). 

Native elements Single element Native metals, native nonmetals... 

The (compositionally) simplest mineral class comprises the native elements, that is, those elements, either metals or nonmetals that occur naturally in the native state, uncombined with others. Native gold, silver, and copper, for example, are metals that naturally occur in a ductile and malleable condition, while carbon - in the form of either graphite or diamond -and sulfur are examples of nonmetallic native elements. Next in compositional complexity are the binary minerals composed of two elements a metal or nonmetallic element combined with oxygen in the oxides, with a halogen - either fluorine, chlorine bromine, or iodine - in the halides, or sulfur, in the sulfides. The oxide minerals, for example, are solids that occur either in a somewhat hard, dense, and compact form in mineral ores and in rocks, or as relatively soft, unconsolidated sediments that melt at moderate to... 

Each of these solid phases can be described in terms of their mineralogy. This classification scheme is based on crystal structure and chemical composition. The most common minerals found in marine sediments are listed in Table 13.2. Most are silicates in which Si and O form a repeating tetrahedral base unit. Other minerals common to marine sediments are carbonates, sulfates, and oxyhydroxides. Less common are the hydrogenous minerals as they form only in restricted settings. These include the evap-orite minerals (halides, borates, and sulfates), hydrothermal minerals (sulfides, oxides, and native elements, such as gold), and phosphorites. 

The extension of the field of native elements (S, C) depends on the adopted... 

Potassium is distributed widely in nature. The metal is too reactive to occur in native elemental form. It is the seventh most abundant element on earth, constituting 2.40% by weight of the earth s crust. It is abundantly present in sea water. Oceans contain 0.07% (wt to volume) potassium chloride. 

Few metals occur in the earth s crust uncombined with others. Those that do, such as gold, silver, mercury, and some copper, are known as the native metals. Together with some native nonmetals such as carbon and sulfur, the native metals make up the relatively small group of native elements, naf-urally occurring masses of single elements that were recognized and put to use by humans in quite early times. Most metals occur in nature combined with nonmetals in the form of mineral and rock deposits, and from fhose minerals they are extracted by means of a variety of metallurgical fechniques. 

An indication of the degree of exothermicity of sulphide oxidation reactions can be gained by comparing the enthalpy of formation (A//f), that is, a measure of the energy locked up in each chemical species, relative to native elements. The difference in enthalpies of formation of all reactants and all products defines the enthalpy (heat released or absorbed) of the reaction. Thermodynamic data on sulphide minerals, such as pyrite, are notoriously varied and disputed, and the values in Table 4 must be treated with caution. Nevertheless, depending on whether one defines the reaction as ending in an aqueous solution (equation 5), an intermediate secondary sulphate (e.g., melanterite - equation 6) or in complete oxidation to an oxyhydroxide (equation 7), the calculated reaction enthalpy (AH°) released is of the order of at least 1000 kJ/mol. 

Carbonates Silicates Phosphates Oxides Native elements... 

Native elements - elements not combined with any other elements. 

Recovered sulfur has grown steadily in importance as a world source of brimstone since the mid 1950 s. Between 1965 and 1977 recovered sulfur s share of world supply grew from 18% to 30% (D and continues to grow in relation to Frasch mined and other forms of native elemental sulfur. All of this has meant a rapid growth in the number of sulfur recovery facilities and new developments in the various techniques and processes associated with the industry. 

SCHULTES R.E. Qs E.W. SMITH, 1980, Plant Hallucinogens Sacred Elements of Native Element, United Communications, Woodmere, NY (Color poster). 

Sulfur is widely distributed as sulfide ores, which include galena, PbS cinnabar, HgS iron pyrite, FeS2 and sphalerite, ZnS (Fig. 15.12). The mineral molybdenite, MoS2, is a soft rock with a metallic sheen and properties similar to those of graphite. Sulfur is also found as deposits of the native element (called brimstone), which are formed by bacterial action on H2S. 

Native elements are minerals composed of a single element. This group also includes natural alloys, which are mixtures of two metals. Based on their physical properties, the native elements can be separated into three divisions metals (such as Ag, Au, Cu, Fe, Hg, Pb, Pt, Sn), semi-metals (such as As, Bi, Sb, Te), and non-metals (C, S, Se). 

Those elements that occur in nature as native elements (minerals). 

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. 

Gold is very stable chemically and seldom forms compounds. The most common and important ore of gold is the native element itself. Native gold often contains small amounts of silver, and sometimes copper or iron. Pure gold is not soluble in any single acid, nor does it tarnish. 

An alloy is a mixture of two or more metals, or of a metal and a non-metal. Many minerals are natural alloys, being compounds of metals or a metal/ non-metal combination. Most of these fall into the native element, sulfide and sulfosalt mineral groups. 

This list is organized according to the chemical composition of mineral species. The simplest, the native elements, are first, followed by progressively more complex minerals. This list only includes those species that are used as gems or ornamental materials. Organic substances, such as amber and jet, are not included and will be addressed elsewhere. 

Native element Diamond c All colors 3.52 2.417 10 Perfect cleavage in four directions... 

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