Formula: (Mg,Ti,Fe,Cr,Al)2O(BO3)
Anhydrous borate, warwickite group
Specific gravity: 3.34 to 3.36
Hardness: 5½ to 6
Streak: Bluish black
Colour: Dark brown, grey to black, coppery tinge on cleavage at times, reddish brown in transmitted light
Solubility: Decomposed in sulphuric acid
Environments
Warwickite is a rare accessory mineral in boron-metasomatised limestone and
associated skarn. Associated minerals include
chondrodite, szaibélyite,
sinhalite, spinel,
diopside, titanite,
dravite, apatite,
fluorite, scapolite,
graphite, magnetite,
ilmenite, pyrite and
pyrrhotite
(HOM).
Localities
At the type locality, Warwick, Orange county, New York, USA, warwickite was initially found as small, rough crystals in the
metamorphosed, crystalline marble known as
Franklin marble, associated with spinel,
magnetite, ilmenite,
graphite, diopside and
chondrodite
(Mindat).
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