Montroyalite

Formula: Sr₄Al₈(CO₃)₃(OH,F)₂₆ ^. 10-11H₂O

Origin of name:  From loality; Mont Royal, Quebec, Canada

Crystal system:  Triclinic

Crystal class:  Unknown

Twinning: 

Unit cell: 

Colour:  White

Diaphaneity:  Translucent

Luster:  Dull to waxy

Habit:  Lath-like grains to 20 µm forming spheres and hemispheres, to 1 mm

Hardness:  3.5

Specific gravity:  2.667

Cleavage:  None

Tenacity: 

Streak:  White

Synonyms/varieties:

Comments:  Soluble in 1:1 HCl; fluoresces white under SW and LW