Goldichite of fumarolic origin from the Santa Barbara Mine, Jujuy, northwestern Argentina (original) (raw)

1995, Canadian Mineralogist

The fust find of goldichite in Argentina and the third worldwide occurrence is described. The mineral was found in a sulfur deposit, the Santa Birbara mine, in iujuy province, formed by present-day activity of thermal springs. The Tioeral occurs with metavoltine, hexahydrite, alunogen, sideronatrite, feninatrite, voltaite, kausite, halotrichite, gypsum and halite. The goldichite @curs as euhedral flattened "ryitats O.:-in lenglh, tabular on { 100}, with t 100}, { 110} and {011} crystallographic forms. The strongest five X-ray powder-diffraction hnJs ld in A(t)(hkt)l are: 10.11(70)(100), 5.11(40X200), 3.072(100)Q02), 2.444A0\h30\. and 2.283i30\e33). The refined unir-cell parameters 6f 1[is 6sn6rslinic mineral arc a 10.397Q), b 10.461(8), c g.tog<qj A, $ rOO.Ootll;, V 972.5(8) A,3. The crystals are transparent, brittle, and have a greenish hue in naturallight and a pale pink'tint onOer uttinaa nght; Orey have a hardness of 2-3, n excellent { 100} cleavage, vitreous luster and white streak. OptiJuUV, goldichite is traasparint, wiih positive elongation, with X colorless, I colorless to very pale yellow, anjlZ very pale y"no*: i j v > x:biaxial (+), 2vbd.\75;,cl 1.584(2), F 1.602Q),y 1,.634Q),X = b, Y'a, Z lt c 9o, v > r, sfong' The chemical composition, obtained by electrotil-microprobe analysii, indicates S, Fe and K as the principal compon€nts, wrJLthe^following ranges in concentration of the oxidei (w.%o):