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Formula: AgHgAsS3
Sulpharsenite
Crystal System: Monoclinic
Specific gravity: 6.11 measured, 6.195 calculated
Hardness: 3½
Streak: Pale cherry-red to brownish red
Colour: Dark red to cherry-red
Environments
Laffittite occurs with other arsenic sulphides in hydrothermal deposits
(HOM).
Localities
At the type locality, Jas Roux, La Chapelle-en-Valgaudemar, Gap, Hautes-Alpes, Provence-Alpes-Côte d'Azur, France,
laffittite occurs as grains up to 0.2 mm in size in dolomitic rocks. Associated
minerals include routhierite, smithite,
stibnite, pierrotite,
parapierrotite, aktashite,
realgar, wakabayashilite,
sphalerite, pyrite and
chabournéite
(AM 60.945-946, HOM).
At the Chauvai Sb-Hg Deposit, Batken Region, Kyrgyzstan, laffittite is associated with
galkhaite, stibnite,
cinnabar, metacinnabar,
sphalerite, fluorite,
calcite and quartz
(HOM).
The Getchell Mine, Adam Peak, Potosi Mining District, Osgood Mountains, Humboldt County, Nevada, USA. Laffittite was found
in a museum specimen labelled getchellite, from the Getchell mine, Humboldt County,
Nevada. The specimen, about 12 x 9 x 6 cm, is a large mass of orpiment, in which
getchellite veinlets are prominent. The laffittite occurs as dark red crystals
in anhedral grains up to 1 mm in length, usually surrounded by getchellite and/or
orpiment. Other associated minerals include
realgar, stibnite which is commonly observed as
inclusions in orpiment, and rarely sphalerite
(AM 68.235-244).
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