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Formula: Ca2B(AsO4)(OH)4
Compound arsenate
Specific gravity: 3.156
Hardness: 3
Streak: White
Colour: Colorless to white, also golden brown; colourless in transmitted light.
Solubility: Readily soluble in dilute hydrochloric acid
Environments:
Pegmatites
Metamorphic environments
Cahnite is a rare arsenate.
Localities
At the Shijiang Shan-Shalonggou mining area, Inner Mongolia, China, the mineral deposits occur predominantly in
veins of hydrothermal origin in skarn. Cahnite was first found here
in association with borcarite as pseudotetrahedral crystals in groups adhering
to the surfaces of much larger borcarite crystal clusters. The cahnite
crystals are greyish white and up to about 2 mm. Later finds were of pseudotetrahedral crystals of cahnite
associated with olshanskyite,
johnbaumite or roweite but not with
borcarite. The crystals of cahnite are white and opaque, to 3 mm, and
have faces that are rough and uneven
(R&M 96.5.400).
At Capo di Bove, Italy, cahnite occurs with zeolites in leucitic lava associated with
phillipsite, chabazite and
calcite
(HOM).
At the Kombat mine, Namibia, cahnite is associated with
natronambulite,
gypsum,
baryte and
calcite
(HOM).
In Siberia, Russia, cahnite is associated with svabite,
magnetite, sphalerite,
garnet and calcite
(HOM).
At the type locality, the Franklin Mine, New Jersey, USA, cahnite is a late-stage mineral in pegmatites cutting a metamorphosed
stratiform zinc orebody, associated with hedyphane,
friedelite,
pyrochroite, franklinite,
willemite, rhodonite,
datolite, axinite,
jarosewichite, samfowlerite,
flinkite, hodgkinsonite,
hetaerolite, hausmannite,
groutite, kentrolite,
garnet and baryte
(HOM , Mindat).
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