Arsenogoyazite

Formula:  (Sr, Ca, Ba)Al₃(AsO₄, PO₄)₂(OH, F)₅^.H₂O

Origin of name:  From arsenic and relation to goyazite

Crystal system:  Hexagonal

Crystal class:  3m or -3 2/m

Twinning:

Unit cell: a = 7.10 Å, c = 17.16 Å

Colour:  White, yellowish pale green to grayish green

Diaphaneity: Translucent to transparent

Luster:  Vitreous

Habit:  Crystals tabular six-sided rhombohedral, aggregated into reniform crusts with radial structure

Hardness:  about 4

Specific gravity:  3.35

Cleavage:  None

Tenacity:

Streak: White

Synonyms/varieties: Weilerite

Comments: Member of the crandallite group. Formed as a secondary mineral in a hydrothermal polymetallic barite-fluorite deposit.