Alforsite

Formula:  Ba₅(PO₄)₃Cl

Origin of name:  For John T. Alfors (1930- ), American geologist, California Division of Mines, for his work on the type locality

Crystal system:  Hexagonal

Crystal class:  6/m

Twinning:

Unit cell: a = 10.284 Å, c = 7.651 Å

Colour:  Colourless 

Diaphaneity: Semi-transparent

Luster: Vitreous

Habit:  Isolated, subhedral microscopic grains, in very fine-grained masses

Hardness: 5

Specific gravity:  4.73-4.80 (calculated)

Cleavage: 

Tenacity:

Streak: White

Synonyms/varieties:

Comments: Member of the apatite group. Found in lenses and bands of barium silicate metasediments developed under hornblende-pyroxene hornfels facies near the contact with granite or granodiorite.