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

Metamorphic environments

Cahnite is a rare arsenate.


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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