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Formula: Cu3(AsO4)2
Anhydrous normal arsenate
Crystal System: Monoclinic
Specific gravity: measured 4.9 - 5.18, calculated 5.236
Hardness: 3½ to 4
Streak: Pale green
Colour: Dark green
Environments
Hydrothermal environments
Fumeroles
Localities
At the type locality, the Laurani mine, Laurani District, Aroma Province, La Paz, Bolivia, lammerite was found
on an old mineral specimen as dark green spheroidal aggregates ~0.5 cm in diameter on corroded
quartz rock associated with olivenite
(Mindat).
At the Tsumeb Mine, Tsumeb, Oshikoto Region, Namibia, lammerite occurs in an oxidised zone in a
dolostone-hosted hydrothermal polymetallic ore deposit. Associated
minerals include chalcanthite,
anhydrite and leightonite
(HOM).
At the Tolbachik volcano, Kamchatka Krai, Russia, lammerite occurs in
fumeroles. Associated minerals
include euchlorine,
melanothallite,
dolerophanite,
chalcocyanite, leningradite,
tolbachite, anglesite,
alarsite, fedotovite,
klyuchevskite, nabokoite,
atlasovite, langbeinite,
hematite and tenorite
(HOM).
All Tolbachik arsenates crystallised at temperatures greater than 450°C (the major assumed temperature interval is
500 to 750°C), under atmospheric pressure. They were precipitated directly from the gas phase as volcanic sublimates,
or were formed as a result of gas–rock interaction in fumaroles, where the host
basalt was the source of the less volatile elements aluminium,
titanium, magnesium and calcium
(EJM 30.305-322).
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