Herbertsmithite

Herbertsmithite forms dark green crystals of rhombohedral habit, with vitreous lustre, = 1.817,

= 1.825, uniaxial negative, weakly pleochroic O > E, density: 3.95 g cm^–3, Mohs hardness: 3–33; space group
R


m
with no superstructure observed, a = 6.834(1), c = 14.075(2) Å, Z = 3; six strongest XRD lines 5.466 (55), 4.702 (14), 2.764 (100), 2.266 (36), 1.820 (13), 1.709 (18).

KEYWORDS: herbertsmithite, paratacamite, anarakite, solid solution, site occupancy and selectivity, new mineral, IR spectroscopy, XRD, Cu chlorides, Anarak, Iran, Sierra Gorda, Chile

Taken from:

http://minmag.geoscienceworld.org/cgi/content/abstract/68/3/527