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Formula: Ca4Fe2+2Al4[B2Si8O30](OH)2
Sorosilicate (Si2O7 groups), axinite group
Crystal System: Triclinic
Specific gravity: 3.25 to 3.28 measured, 3.33 calculated
Hardness: 6½ to 7
Streak: White
Colour: Brown, clove-brown, plum blue, pearl grey
Solubility: Insoluble in water, hydrochloric, nitric and sulphuric acid
Environments:
Plutonic igneous environments
Pegmatites rarely
Metamorphic environments
Hydrothermal environments
Axinite-(Fe) is found in quartz - calcite
veins,
in alpine-type veins, as shear zone mineralisation, especially in high grade metamorphic zones, as hydrothermal metasomatism of
granite or aplite, rarely in
granite pegmatites, and in the
contact zones surrounding
granite intrusions
(Dana).
Associated minerals include epidote -
clinozoisite,
grossular, vesuvianite,
ilvaite, hedenbergite,
hastingsite, andradite,
zoisite, actinolite,
datolite, tourmaline,
calcite, albite,
quartz, danburite,
prehnite, titanite,
plagioclase, microcline,
arsenopyrite, pyrite and
zeolites
(Dana, HOM).
Rarely, axinite-(Fe) may be replaced by clinochlore -
chamosite or clay minerals
(Dana).
Localities
At Nandan County, Hechi, Guangxi, China, axinite-(Fe) has been found as dark brown, transparent, vitreous to metallic,
prismatic crystals up to 4 mm long on a chalky white matrix
(AESS).
Axinite-(Fe) from Nandan County - Image
The type localities is Saint Christophe-en-Oisans, Isère, Auvergne-Rhône-Alpes, France.
At the Belvidere Mountain Asbestos Quarries, Lowell/Eden, Vermont, USA, a specimen has been found with crystals of
axinite-(Fe) to
2 cm associated with epidote and chrysotile
(R&M 90.6.527).
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