Mineralpedia Details for Axinite-(Mn)

Previously called Manganaxinite, this mineral is named for the dominance of manganese in the chemical formula and as a member of the Axinite Group, which in turn received its name from the Greek word for “axe” in reference to the sharp crystal habit. Axinite-Mn is an uncommon mineral that is formed by contact metamorphism and boron metasomatism, and can also be found in pegmatite veins in contact with metamorphosed iron formations and gabbro. Localities for Axinite-Mn include Germany, Ireland, Italy, the United States, Cananda, and Japan, among others.

Ref. Handbook of Mineralogy, Anthony et al (1995) and MSA at http://www.handbookofmineralogy.org/pdfs/manganaxinite.pdf

Formula

Ca₂Mn²⁺Al₂BSi₄O₁₅(OH) 

Crystal System

Triclinic 

Crystal Habit

Massive - Granular, Lamellar 

Cleavage

Distinct, Poor, Poor 

Luster

Vitreous (Glassy) 

Color

brown, colorless, yellowish, pale violet, reddish 

Streak

white 

Class

Triclinic - Pinacoidal 

Fracture

Brittle - Conchoidal 

Hardness

6.5-7 

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Green-brown thin tabular "axe-head" Manganaxinite crystals to 3mm.

Golden honey colored, tabular Axinite crystals to 3mm associated with prismatic, light green Datolite, and glassy pink Rhodochrosite.