A New Occurrence of Vesigniéite from the Gorob-Hope Copper Deposit, Namibia

G. I. C. Schneider and H. -J. Lauenstein
Geological Survey of Namibia P.O. Box 2168 Windhoek 9000, Namibia
Tsumeb Corporation P.O. Box 40 Tsumeb 9000, Namibia

Abstract: An iron-rich vesigniéite, [Ba(Cu,Fe)3(VO4)2(OH)2] with Cu : Fe near 4 : 1, was identified in samples from the submarine-exhalative Gorob-Hope copper deposit, Namibia. The olive-colour mineral occurs as mammillary encrustations and vein fillings in the gossan zone of this deposit; it often has a brownish oxidation coating. The main X-ray lines are 3.21 Å (100) [204, 113], 2.72 Å (63) [313, 002] and 2.94 Å (61) [020, 311]. The cell parameters are a = 10.236, b = 5.905, c = 14.253 Å and ß = 103.71°. The formation of vesigniéite took place during the alteration of the ore under strongly alkaline and slightly reducing to oxidizing conditions. While copper and barium were derived from the submarine exhalative mineralisation, vanadium was leached from the countryrock, a micea schist.

Keywords: vesigniéite • vanadate • Gorob-Hope deposit • Namibia

Mineralogical Magazine; March 1992 v. 56; no. 382; p. 67-69; DOI: 10.1180/minmag.1992.056.382.07
© 1992, The Mineralogical Society
Mineralogical Society (www.minersoc.org)