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Formula: Cu4(SeO3)(SO4)(OH)4.2H2O
Hydrated sulphate, selenium-bearing mineral
Crystal system: Triclinic
Specific gravity: 3.535 calculated for the empirical formula, 5.361 for the ideal formula
Hardness: 2
Streak: Pale green
Colour: Green
Luminescence: No fluorescence under UV
Solubility: Rapidly soluble in room-temperature, dilute hydrochloric acid
Common impurities: Zn
Environments
Localities
At the type locality, the Santa Rosa Mine, Malpais Mesa, Inyo Mts, Inyo County, California, USA, the ore-bearing veins
are highly oxidised and consist mainly of cerussite and
hemimorphite in a gangue of
limonite, jasper and
calcite. The small amount of remaining
primary ore contains mainly
galena, sphalerite,
pyrite, chalcopyrite and
arsenopyrite, in order of decreasing abundance.
Pauladamsite occurs on limonitic
gossan matrix consisting mainly of
goethite, hematite,
hemimorphite, hetaerolite,
K-feldspar and quartz. The
occurrence is along the margin of a massive sulphide body in contact with coarse-grained
marbles and garnet
skarn. Galena in the sulphate
stope is rich in selenium and locally was observed altering to
cerussite and native selenium. A
number of trace accessory phases that contain selenium also occur as
inclusions in sphalerite; these include
aguilarite, bohdanowiczite,
clausthalite, geffroyite,
krut’aite, naumannite and
tetradymite. Pyrite, with minor
amounts of selenium-bearing
covellite and traces of
clausthalite, is the
primary sulphide most closely associated with
pauladamsite and maybe the source of selenium. Other
secondary minerals found associated closely with
pauladamsite include brochantite,
chalcanthite, gypsum,
kobyashevite, ktenasite,
mimetite, schulenbergite and
smithsonite.
Other secondary minerals identified in the general assemblage
are antlerite, boyleite,
brianyoungite, devilline,
hydrozincite, lahnsteinite,
osakaite and posnjakite.
Pauladamsite occurs as green blades grouped in radial sprays; the elongated blades are up to 0.5mm long
(MM 80.6.949-958).
Pauladamsite from the Santa Rosa Mine -
Image
At the Burro Mine, San Miguel County, Colorado, USA, pauladamsite occurs as green acicular sprays with light
blue devilline, dark blue
chalcomenite and lime-green
volborthite
(Mindat photo)
Pauladamsite from the Burro Mine - Image
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