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Formula: 6(Fe0.9S).5[(Mg,Fe)(OH)2]
Sulphide, valleriite group
Crystal System: Monoclinic
Specific gravity: 2.96 to 2.99 measured, 3.03 calculated
Hardness: 1 to 1½
Colour: Bronze-black
Environments
Plutonic igneous environments
Meteorites
Tochilinite occurs in sulphide-rich serpentinised
ultramafic bodies, where it may be abundant, in
diamond pipes and in some carbonaceous
chondrite meteorites
(HOM, Webmin).
Localities
At Bancroft, Ontario, Canada, tochilinite is associated with
pyrrhotite, forsterite,
clinohumite,
hydromagnesite,
graphite and calcite
(HOM).
At the type locality, the Nizhnii Mamon Cu-Ni Deposit, Nizhnii Mamon Village, Upper Don River, Voronezh Oblast,
Russia, tochilinite occurs as radiating aggregates of cylindrical acicular crystals, which may be hollow, to
1 cm, as paper-thin coatings, as felted masses and as clots (Mindat). It has been found in
lizardite from drill cores (AM 57.1552).
Associated minerals include troilite,
pyrrhotite, sphalerite,
calcite and lizardite
(HOM ).
At Hunting Hill quarry, Maryland, tochinilite is found rarely as prismatic crystals or sprays to 1.1 cm on
calcite
(Minrec 36.5.444).
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