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Formula: Zn7Cu(OH)13[SiO(OH)3(SO4)]
Sulphate, namuwite group
Crystal System: Trigonal
Specific gravity: 3.45 measured, 3.51 calculated
Hardness: 2 to 3
Streak: White
Colour: Light green, ice-blue, colourless
Environments
Localities
At the Frongoch Mine, Pontrhydygroes, Upper Llanfihangell-y-Creuddyn, Ceredigion, Wales, UK, bechererite occurs
as a post-mine mineral associated with susannite,
hemimorphite, namuwite and
cerussite
(HOM).
The type locality, the Tonopah-Belmont mine, Belmont Mountain, Tonopah, Osborn Mining District, Maricopa county, Arizona, USA,
is hosted in a structurally isolated block of rocks that is in fault contact on one side with
granite and on all other sides it is surrounded by
phyllite. The mine is a hydrothermal gold
and silver base metal vein deposit, and
primary ore minerals are galena,
chalcopyrite, sphalerite,
gold, silver and
hematite. The alteration of these
primary minerals yielded a suite of at least 30
secondary minerals.
Bechererite occurs as a secondary mineral, as thin elongated
crystals, commonly in hemispherical aggregates. It is associated with willemite and
rosasite, which crystallized earlier, and
hydrozincite as the latest mineral in this sequence. In one of four vugs
investigated, smithsonite,
paratacamite and boleite were also found
(AM 81.244-248, Mindat).
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