Axinite series

Formula:  Ca₂(Fe, Mn)Al₂BSi₄O₁₅(OH)

Origin of name:  From Greek axine = axe

Crystal system:  Triclinic

Crystal class:  -1

Twinning:

Unit cell:

Colour:  Various shades of brown with reddish or purplish overtones, also bluish-gray, orange-yellow, pink, or colourless

Diaphaneity: Transparent to translucent

Luster:  Vitreous

Habit:  Crystals, flattened, tabular with knife-like edges; also fibrous, granular; or massive

Hardness:  6.5 to 7

Specific gravity:  3.2 to 3.3

Cleavage:  4; {100} good, {001}, {110} and {011} poor

Tenacity:

Streak: White

Synonyms/varieties:

Comments:  See also the end-members of the axinite series: ferro-axinite and manganaxinite