Tiragalloite

Formula: Mn₄AsSi₃O₁₂(OH)

Origin of name: for Paolo Tiragallo (1905- ), Italian amateur mineralogist

Crystal system: Monoclinic

Crystal class: 2/m

Twinning: On {100}

Unit cell: a = 6.66, b = 19.92, c = 7.61, β = 95.7°

Colour: Orange, brownish orange

Diaphaneity: Transparent to translucent

Luster: Subadamantine

Habit: small grains between 0.2 and 1.5 mm,which may be elongated, in aggregates 4 to 6 mm

Hardness: 

Specific gravity: 3.84

Cleavage: 2; {100} good, parting distinct, normal to elongation

Tenacity: 

Streak: White

Synonyms/varieties:

Comments:  Found in veinlets cutting massive braunite and quartz.