Natural minerals

Petroleum—a natural mineral oil—was referred to as early as the Old Testament. The word petroleum means rock oil [from the Greek petros (rock) and elaion (oil)]. It has been found for centuries seeping out of the ground, for example, in the Los Angeles basin in what are now called the La Brea tar pits. Vast deposits were found in Europe, Asia, the Americas, and Africa. 

Cryolite. Cryohte constitutes an important raw material for aluminum manufacturing. The natural mineral is accurately depicted as 3NaF AIF., but synthetic cryohte is often deficient in sodium fluoride. Physical properties are given in Table 4. 

With few exceptions, extender pigments can be classified as commodity chemicals. They are manufactured in large quantities with less sophisticated production methods than most pigments. Whereas the majority of pigments is prepared synthetically, extender pigments are mainly manufactured by the beneficiation of natural minerals. Based on chemical composition, extender pigments are carbonate, sulfate, siUca-based, and siUcate-based compounds. 

Potassium sulfate is produced in Sicily by controlled decomposition of the natural mineral kainite, KCl-MgS04-2.75H2 0 (26). This salt is first converted to schoenite in an aqueous solution from a potassium sulfate conversion step. A similar process is used in the United States. Kainite is obtained as the potassium feedstock by stage evaporation of Great Salt Lake bitterns (see Chemicals frombrines). 

The known uranium(VI) carbonate soHds have empirical formulas, 1102(003), M2U02(C03)2, and M4U02(C03)3. The soHd of composition 1102(003) is a well-known mineral, mtherfordine, and its stmcture has been determined from crystals of both the natural mineral and synthetic samples. Rutherfordine is a layered soHd in which the local coordination environment of the uranyl ion consists of a hexagonal bipyramidal arrangement of oxygen atoms with the uranyl units perpendicular to the orthorhombic plane. Each uranium atom forms six equatorial bonds with the oxygen atoms of four carbonate ligands, two in a bidentate manner and two in a monodentate manner. 

Separation of Hafnium. Zirconium and hafnium always occur together in natural minerals and therefore all zirconium compounds contain hafnium, usually about 2 wt % Hf/Hf + Zr. However, the only appHcations that require hafnium-free material are zirconium components of water-cooled nuclear reactors. 

Bromine is widely distributed ia nature but ia relatively small amounts. Its abundance ia igneous rock is 0.00016% by weight and ia seawater is 0.0065% by weight. The only natural minerals that contain bromine are some silver haUdes, including bromyrite [14358-95-3] embolite [1301-83-3], Ag(Cl,Br),... 

Magnesium oxide. The natural minerals, i.e., magnesite (MgCO ), brucite [Mg(OH)9], etc., after being crushed to predetermined size, are calcined at temperatures varying from 1055 to 2000 K, depending upon whether a caustic or a dead-burned produc t (periclase) is being... 

What property held in common by the following compounds accounts for their presence in natural mineral deposits MgC03, CaC03, SrC03, BaS04, and (in bones) Ca PO ... 

The wide variety of natural minerals with [2 x 2] tunnels already indicates that a huge number of different compounds of the a-Mn02 type can be obtained by a laboratory synthesis. Most chemical syn-... 

A large number of natural mineral and synthetic materials with a layered structure and strongly varying water and foreign-... 

T1(I), Pb(II) and Bi(III) are mainly found in natural minerals predominantly in the form of sulphide ores and rarely as sihcates [20, 21]. 

In contrast to SCCO2, the conditions required to obtain SCH2O are harsh. In particular the temperature requirement of 374 °C precludes its synthetic utility for most organic compounds. That said, syntheses in sub-critical but high-temperature water are well studied and will be covered in the next section. Since many natural minerals and precious stones were formed in water at high temperature and pressure in the Earth s crust, the synthesis... 

Formerly derived from the natural mineral lapis lazuli, ultramarine blue pigments have, for more than a century, been manufactured synthetically. The materials used in the manufacture of ultramarines are china clay (a hydrated aluminosilicate), sodium carbonate, silica, sulfur and a carbonaceous reducing material such as coal tar pitch. For the manufacture of the blue pigments, the blend of ingredients is heated to a temperature of 750 800 °C over a period of 50-100 h, and the reaction... 

Philosophers of Nature. Mineral lesson 23. fhttp //rare-earth-minerals.com/1. 

When it consists of only silica and water, flint is basically colorless. Impurities within the stone, however, render colored varieties. Thus, much flint is tan, beige, or jet black with a brown homy appearance (the latter color is caused mainly by iron impurities), but there are also gray, pink, and even red varieties. If dark flint is heated to temperatures above 450°C, the outer layer changes to white. Flint that underwent such a heating process is known as burned or calcinated flint, a misnomer probably used because the white surface appears to have changed into lime (Luedtke 1992 Sieveking and Bart 1986). Burned flint is easier to work than is the natural mineral, a property... 

This same technique should be helpful in understanding wetting properties important in the oil industry since wetting is very dependent on mineral surface energies. The use of contact angle hysteresis information may allow a better understanding of the effects of surface heterogeneities of natural mineral samples. The dynamic Wilhelmy plate technique is ideally suited for such experiments ... 

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