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Formula: Ca4Mn2+2Al4[B2Si8O30](OH)2
Sorosilicates (Si2O7 groups), axinite group,
manganese-bearing mineral
Crystal System: Triclinic
Specific gravity: 3.306 to 3.358 measured, 3.31 calculated
Hardness: 6½ to 7
Streak: White
Colour: Brown, golden-yellow
Solubility: Insoluble in water, hydrochloric, nitric and sulphuric acid
Common impurities: Ti,Fe,Mg,Na,K,H2O
Environments:
Pegmatites
Metamorphic environments
Hydrothermal environments
Axinite-(Mn) is found in quartz - calcite
veins, igneous contact zones especially with
mafic
rocks and some granite pegmatites
(Dana). It is typically formed by contact metamorphism and boron
contact metasomatism
(HOM).
Associated minerals include quartz,
plagioclase,
microcline, chamosite,
spessartine, andradite,
johannsenite, rhodonite,
tourmaline, chlorite,
K-feldspar and datolite
(Dana, HOM).
Localities
In Minnesota, axinite-(Mn) has been found in a pegmatite vein cutting metamorphosed iron formation at a
contact with gabbro
(HOM).
At the type locality the Franklin Mine, Franklin Mining District, Sussex County, New Jersey, USA, axinite-(Mn) occurs
in a zinc-iron
polymetalic metamorphosed deposit hosted by marble. Associated minerals include
rhodonite, hendricksite,
hancockite, baryte and
andradite
(Mindat).
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