Peacock ore

The colour is the most obvious and conspicuous external property of a large number of minerals. Minerals are distinguished by an extraordinary variety of colours and shades of varying richness and intensity. Some mineral species are characterised by a constant colour, which enables one to detect them almost unerroneously. Just as an example, mention may be made of a sulphidic mineral of copper, bomite (Cu5FeS4). The best identifying feature of this mineral is its purplish-blue tarnish over a bronze colour ( peacock ore). 

Cuprous ferric sulphide, Cu2S.FeaS3, occurs in nature as copper pyrites, cholcopyrite, or towcmite, and is one of the commonest ores of copper (see p. 23). It is tetragonal, possessed of a brass-yellow colour, and exhibits a conchoidal fracture. It is decomposed by nitric acid, and tarnishes upon exposure to air, frequently yielding beautiful iridescent surfaces, a blue colour predominating. Masses of such tarnished ore are found in Cornwall, and arc known as peacock ore. The blue colour is probably due to the formation of a surface layer of cupric sulphide or covellite, CuS. 

PDGF See GROWTH eactor. peacock ore SeeBORNiTE. peak oil The point at which global oil pro-... 

Various well-known industrial and municipal waste products particularly those from the base metal industry, contain appreciable amounts of Fe oxides which may make them suitable for remediation purposes. Two examples from industry are the residues from the alumina and the titanium industries. The extraction of either Al or Ti from the natural ores (bauxite and ilmenite/rutile, respectively) leaves behind an alkaline and acidic (sulphuric) residue, respectively, in which Fe oxides are enriched, as indicated by their names Red Mud and Red Gypsum . A sample of Red gypsum is reported to contain ca. 35% of Fe oxide consisting of goethite and hematite, half of which was oxalate soluble (Fauziah et al., 1996). As expected, this material had an appreciable adsorption capacity for phosphate and heavy metals and, if added to soils, could confer these properties on them (Peacock Rimmer, 2000),... 

Bomite CujFeS reddish-brown iridescent purple Peacock" copper ore... 

---