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Formula: Pb3Sb2S6
Sulphosalt, antimony-bearing mineral
Crystal System: Monoclinic
Specific gravity: 6.24 measured, 6.25 calculated
Hardness: 2 to 3
Streak: Black
Colour: Grey-black to lead-black
Luminescence: Not fluorescent under UV
Environments
Localities
At the Pinnacles Mine, Broken Hill district, Yancowinna county, New South Wales, Australia, the
lead-zinc sulphide deposit appears to be
a metamorphosed exhalative deposit similar to the main Broken Hill lode, though much smaller. The deposit occurs in
high-grade metamorphic rocks, mainly gneisses of
granulite facies grade, and consists of a
lead-rich lode overlain and underlain by weakly developed
zinc lodes. In 1984, a near-surface extension to the
lead lode was located and is being worked from a small open-pit.
Galena-rich ore from this location has higher-than-average
silver values and was found to contain minor
freibergite, pyrargyrite,
trace famatinite and falkmanite.
Falkmanite occurs as irregular and subhedral prismatic grains, less than 1.2 mm long, within
galena. It is intimately associated with irregular intergrowths and veins of
minor pyrargyrite as well as small grains, less than 0.05 mm. of
famatinite. The ore sample containing falkmanite has undergone
some incipient oxidation and shows narrow zones and patches of anglesite
along fractures in galena and around the margins of other mineral inclusions.
Where galena is unaltered, falkmanite and
pyrargyrite show mutual boundaries with
galena. Famatinite generally
occurs around the edges of falkmanite grains and is intergrown with fine-grained
galena or anglesite after
galena. Associated gangue minerals
are quartz, spessartine
garnet, calcite and
gahnite. Freibergite occurs as
small inclusions in galena from the same part of the
lead lode but is not present in the sample containing falkmanite.
Boulangerite, meneghinite,
bournonite and jamesonite,
which are more cornmon sulphosalts in the Pinnacles ores, are also absent from this sample
(CM 25.15-19).
At Minas Gerais, Brazil, falkmanite occurs with pyrite in
quartz
(AM 25.312).
At the type locality, the Bayerland mine, Pfaffenreuth, Leonberg, Tirschenreuth District, Upper Palatinate, Bavaria,
Germany, falkmanite has been found as fibrous aggregates associated with
galena, jamesonite,
bournonite, geocronite,
arsenopyrite,
chalcopyrite, sphalerite,
pyrrhotite, pyrite,
tetrahedrite and valleriite
in a quartz gangue
(AM 25.312).
At Sala, Sala Municipality, Västmanland County, Sweden, Sala, Sweden, falkmanite occurs with
galena and pyrite
(AM 25.312).
At the Boliden mine, Boliden, Skellefte mining district, Skellefteå, Västerbotten County, Sweden, falkmanite
occurs with numerous other minerals, chiefly bournonite,
galena, danaite,
pyrite, chalcopyrite,
tetrahedrite, bismuth,
gudmundite and jamesonite
(AM 25.312).
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