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Formula: Mn2+BO2(OH)
Anhydrous metaborate containing hydroxyl, forms a series with
szaibélyite
Crystal System: Orthorhombic
Specific gravity: 3.30 measured, 3.43 calculated
Hardness: 3
Streak: White
Colour: White, lilac/lavender, black (perhaps due to alteration or inclusions), also golden-brown; colourless in transmitted light
Solubility: Slowly soluble in acids
Common impurities: Mg
Environments:
Metamorphic environments
Hydrothermal environments
Sussexite is a hydrothermal mineral typically in veinlets in boron-bearing metamorphosed
manganese-iron-zinc
deposits
(Webmin, HOM), associated with pyrochroite,
rhodochrosite, wiserite,
hausmannite, sonolite,
alabandite, seamanite,
tephroite, alleghanyite,
willemite, leucophoenicite and
hauckite
(HOM).
Localities
At Iron county, Michigan, USA, sussexite is associated with seamanite, occurring
in thin veinlets 1mm to 3mm wide. The veins run through both hematite ore and highly altered,
porous cherty gangue. Small cavities within the veins are lined with crystals of
seamanite, in many instances implanted directly upon sussexite
(AM 19.575).
Sussexite has three co-type localities, the Hamburg mine, the Trotter mine, and the Franklin mine itself, all at Franklin,
Franklin Mining District, Sussex county, New Jersey, USA. Here sussexite occurs in hydrothermal veinlets traversing a Precambrian
metamorphosed
zinc-manganese-iron
orebody, associated with willemite,
rhodochrosite, pyrochroite and
leucophoenicite (Mindat). A specimen has been found at Franklin furnace
consisting chiefly of willemite, franklinite
and zincite with a coating of fibrous sussexite
(AM 9.188).
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