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ERUBESCITE

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Originally appearing in Volume V09, Page 757 of the 1911 Encyclopedia Britannica.
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ERUBESCITE , a native See also:

copper-See also:iron sulphide, Cu5FeS4, of importance as an ore of copper. It crystallizes in the cubic See also:system, the usual See also:form being that of interpenetrating cubes twinned on an octahedral See also:plane. The faces are usually curved and rough, and the crystals confusedly aggregated together. Compact and granular masses are of more frequent occurrence. The See also:colour on a freshly fractured See also:surface is bronzy or coppery, but in moist See also:air this rapidly tarnishes with iridescent See also:blue and red See also:colours; hence the names See also:purple copper ore, variegated copper ore (Ger. Buntkupfererz), See also:horse-flesh ore, and erubescite (from the See also:Lat. erubescere, " to grow red "). The lustre is metallic, and the streak greyish-See also:black; hardness 3; sp. gr. 5.0. Bornite (after See also:Baron Ignaz von See also:Born, b. 1742, d. 1791) is a name in See also:common use for this See also:mineral, and it predates erubescite, the name given by J. D.

See also:

Dana in 185o, but afterwards rejected by him; See also:French authors use the name See also:phillipsite, after the See also:English mineralogist, R. See also:Phillips, who analysed the mineral; both these earlier names had, however, been previously used for other minerals. Owing to the frequent presence of mechanically admixed chalcopyrite and chalcocite, the published analyses of erubescite show wide See also:variations, the copper, for example, varying from 50 to 70%. Even the best Cornish crystals enclose a See also:nucleus of chalcopyrite (CuFeS2), and an See also:analysis of these made in 1837 led to the See also:long-accepted See also:formula Cu3FeS3. Recently, B. J. See also:Harrington has analysed carefully selected material and obtained the formula Cu5FeS4. Erubescite occurs in copper-bearing See also:veins, and has been See also:mined as an ore of copper' at See also:Redruth in See also:Cornwall, See also:Montecatini in the See also:province of See also:Pisa, See also:Tuscany, See also:Bristol in See also:Connecticut, See also:Acton in See also:Canada, and other localities in See also:North See also:America. The best crystallized specimens are from the Carn Brea mine and other copper mines in the neighbourhood of Redruth, and from Bristol in Connecticut. Recently a few large isolated crystals with the form of icositetrahedra have been found with See also:calcite and See also:albite in a See also:gold-vein on Frossnitz-Alpe in the See also:Gross-Venediger, See also:Tirol. (L. J.

End of Article: ERUBESCITE

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