Is Hauy's "cuivre sulfate" then chalcanthite, brochantite or antlerite
? What is "cuivre gris" that is treated by Hauy as an isomorph of "cuivre pyriteux"?
The original deposit possessed a leached capping of oxide ore averaging some 27 m in thickness, the principal minerals being malachite, azurite, cuprite, tennantite, brochantite, antlerite
However, scientists noticed in 1986 that the surface also contained lots of a sulfur-enriched mineral called antlerite
([Cu.sub.3][(OH).sub.4][SO.sub.4]), which dissolves and washes away more easily than brochantite, exposing the darker layer below (SN: 12/20 & 27/86, p.392).
A dealer may advertise antlerite
as a rare species but fail to mention that at Chuquicamata, in northern Chile, home of the largest open-pit copper mine in the world, antlerite
is a common ore mineral.
X-ray diffraction studies show thatthe green patina consists largely of two basic copper sulfates: brochantite, CuSO.sub.4..3Cu(OH).sub.2., and antlerite
Green acicular crystals of antlerite
coating quartz were found on upper levels of the Salvadora vein (Bandy, 1944).
Baboian's results suggest that acid rain may be converting a stable form of basic copper sulfate called brochantite, CuSO4 3Cu(OH)2, which formed naturally on the statue's copper surface, into a less stable form of copper sulfate called antlerite
, CuSO4 2Cu(OH)2.
A single amazing specimen which emerged from the find consists of a discrete, gemmy red cuprite crystal, 2.6 cm on edge, sitting up smartly on a green bed of antlerite
microcrystals over massive cuprite: this incredible specimen was the talk of the 1987 Tucson show, and was published on the cover of vol.
Imagine their joy when they broke into a treasure pocket containing an amazing, totally gemmy, 1-inch cuprite crystal sitting on antlerite
. The boulder eventually yielded some 20 different species but the prize was the finest cuprite in the world.
Associated minerals are: gypsum, cuprite, antlerite
, goethite, lepidocrocite, mbobomkulite, hydrom-bobomkulite, sklodowskite and two undefined uranium minerals.
Conversely, a number of species occurring at the Blanchard mine (antlerite
, cinnabar, hydrozincite, sulfur, mottramite, otavite, and cuprite) have not been found at the Mex-Tex mine.