Tin-bearing minerals

The rutile lattice is adopted by Sn02 cassiterite, the most important tin-bearing mineral), Mn02 (pyrolnsite) and Pb02. 

A number of tin-bearing minerals have been examined, but the broad line [Refs, on p. 424]... 

Tantalum is found in a number of oxide minerals, which almost invariably also contain niobium (columbium). The most important tantalum-bearing minerals are tantalite and columbite. which are variations of the same natural compound (Fe, Mn)(Ta, Nb Og. Much of the tantalum concentrates has been obtained as a byproduct from tin mining in recent years, tin slags, which are a byproduct of the smelting of cassiierite ores, such as those found in the Republic of Congo. Nigeria, Portugal. Malaya, and Thailand have been an important raw material source for tantalum. 

Hafnium is more abundant than uranium and tin in the Earth s crust, with 5.3 ppm wL As previously discussed, the close chemical similarity between hafnium and zirconium leads to their parallel association in natural ores and minerals where hafnium is invariably found in zirconium ores in quantities of between 1 and 2 wL%. Apart from specific zirconium ores such as zircon or baddeleyite where hafnium is always present, chief and specific hafnium-bearing minerals are rare the nesosilicates Ho/hon [HfSiOJ and Alvite [(Hf, Zr, ThlSiO xH O]. 

Platinum occurs in nature as a bright-white cubic crystalline solid with metallic luster associated with other noble metals of its group. Platinum also occurs as the mineral sperrylite, PtAs2, found as tin-white brittle cubic crystals containing 52-57% platinum in certain nickel-bearing deposits. Some other minerals of platinum are cooperite PtS (Pt 80-86%) and braggite(Pt, Pd, Ni)S (Pt 58-60%). The abundance of platinum in the earth s crust is estimated to be 0.005 mg/kg. 

History.—Until the middle of the eighteenth century both scheelite and wolframite were considered to be ores of tin their real identity was first pointed out in 1781 by Scheele, who show ed that the mineral now bearing his name contained lime combined with a new acid, which he named tungstic acid. The metallic nature of the element was first demonstrated by Bergman. Further researches were undertaken by D Elhuyart, Juan, Jose, and others. The preparation of metallic tungsten, its industrial application (especially with regard to electrical glow lamps), and the study of its compounds have since been the subject of numerous researches. 

Romarchite is a tm(II) oxide mineral with composition SnO. It is a secondary mineral which occurs as thin soft black crusts with metallic lustre, or as microscopic laths, formed as a weathering product of tin compounds. It was first reported by Organ and Mandarine (1971) as a corrosion product of tin pannikins which had been immersed in water at Boundary Falls (Ontario, Canada). Romarchite is named after the acronym for the Royal Ontario Museum of archaeology, and is often found in association with the hydroxyl-bearing form hydroromarchite, which also has tetragonal symmetry. 

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