Trembathite

trembathite

halite

hilgardite

boracite

Images

Formula: Mg₃B₇O₁₃Cl
Anhydrous borate containing halogen, boracite group, paramorph of boracite
Crystal System: Trigonal
Specific gravity: 2.84 to 3.34 measured, 3.225 calculated
Hardness: 6 to 8
Streak: White
Colour: Colourless to pale blue
Common impurities: Mn,Ca
Environments

Evaporite deposits

Trembathite is a rare component of marine evaporite borate deposits (Webmin).

Localities

At the type locality, the Clover Hill deposit, Salt Springs evaporite deposit, Hammond Parish, Kings county, New Brunswick, Canada, trembathite occurs as a rare component of the marine evaporite borate deposit, associated with halite and hilgardite (HOM).

At the Boulby Mine, Loftus, Redcar and Cleveland, England, UK, in evaporite deposits, trembathite occurs as superb crystals to 2 cm on sylvite and halite rock matrix. The borate minerals boracite, trembathite and congolite are stable at room temperature, but ericaite requires a temperature above about 70^oC for stability; below this temperature it alters to congolite (M&M 25.31-32, supplement to Minrec 41.1).

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