Formula: Ca2Pb3(AsO4)3Cl
Anhydrous arsenate containing halogen, hedyphane group, apatite supergroup
Specific gravity: 5.82
Hardness: 4½
Streak: White
Colour: White, yellow-white, bluish
Solubility: Soluble in nitric acid

Metamorphic environments
Hydrothermal environments

Hedyphane is a relatively rare secondary arsenate found in metamorphosed manganese deposits.

At Långban, Värmland, Sweden (the type locality), hedyphane occurs filling fissures in a garnet-pyroxene matrix (Mindat), associated with baryte, barylite, rhodonite, hausmannite, bixbyite, phlogopite, amphibole and calcite (HOM, AM 69.920-927). Specimens have been found consisting of massive, calcite-bearing rock, coated with calcite crystals. These are, in turn, coated with hedyphane crystals, followed by sparse amounts of allactite and two generations of hausmannite (AM 69.920-927).

At Pajsberg, Värmland, Sweden, hedyphane occurs with tephroite and calcite in magnetite (Dana).

At Franklin, New Jersey, USA, hedyphane is the most abundant non-silicate lead mineral, associated with barylite, calcite, willemite, native copper, native lead, hancockite, rhodonite, baryte, axinite-(Mn), apatite and cahnite in veinlets in a metamorphosed zinc orebody (Dana, HOM). In some specimens hedyphane is the chief mineral, forming the matrix for the other species; in others calcite encloses the other minerals (AM 10.351). Specimens of hedyphane from the Parker Shaft, Franklin mine, contain hedyphane associated with axinite, grossular and hancockite (AM 12.180).

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