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Formula: Au(Bi,Pb)5S4
Sulphosalt, bismuth-bearing mineral
Crystal System: Monoclinic
Specific gravity: 8.64 calculated
Hardness: 2½ to 3
Streak: Black
Colour: Tin-white
Environments
Jonassonite is a relatively new mineral, approved in 2004, and occurring in
sulfide/arsenide/selenide veins
(Mindat).
Localities
At the North British mine, Maldon, Mount Alexander Shire, Victoria, Australia, jonassonite occurs as
microscopic grains with other
bismuth-tellurium phases in
millimetre-sized patches in seamy quartz, associated with native
bismuth and joséite-B
(AJM 15.32-33).
At the type locality, Nagybörzsöny, Szob District, Pest County, Hungary, jonassonite was detected in old
mining dumps of the abandoned deposit. The mineralisation is hosted by calc-alkaline volcanic rocks and occurs as
a stockwork in a propylitised
dacite breccia pipe. The
assemblage of metallic minerals with which jonassonite is associated consists of
arsenopyrite, pyrite,
marcasite, pyrrhotite,
sphalerite, chalcopyrite, native gold, native bismuth,
bismuthinite, ikunolite,
cosalite, lillianite and
possibly cannizzarite.
Jonassonite occurs as anhedral grains
of up to 500 × 150 μm, and contains inclusions of native bismuth,
ikunolite and bismuthinite
(CM 44.1127-1136).
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