Arsenocrandallite

Formula:  (Ca,Sr)Al₃(AsO_4,PO₄)₂(OH)₅^.H₂O

Origin of name:  From arsenic and  relation to crandallite

Crystal system:  Hexagonal

Crystal class:  -3 2/m or 3m

Twinning:

Unit cell: a = 7.06-7.08 Å, c = 17.22-17.27 Å

Colour:  Blue to blue-green

Diaphaneity: Semitransparent

Luster:  Vitreous

Habit:  Reniform crusts and spherulitic aggregates

Hardness:  About 5.5

Specific gravity:  3.25

Cleavage: None

Tenacity:

Streak: White

Synonyms/varieties:

Comments: Member of the crandallite group. Formed as a secondary mineral on specimens from a mine-dump (Neubulach, Germany).