Hydrated borate containing halogen, hilgardite group
Specific gravity: 2.67 to 2.71
Colour: Colourless, light pink; colourless in transmitted light
Hilgardite is a minor borate mineral in marine evaporite deposits
At New Brunswick, Canada, hilgardite is associated with boracite and szaibélyite (HOM).
At the Boulby potash mine, Loftus, North Yorkshire, England, UK, hilgardite occurs with volkovskite (R&M 91-5.434-441), and hilgardite pseudomorphs after boracite have been found (KL p186).
At the type locality, the Choctaw Salt Dome, Plaquemine, Iberville Parish, Louisiana, USA, hilgardite occurs in the salt dome associated with boracite, anhydrite, danburite, dolomite, magnesite, pyrite, hauerite, calcite, quartz, sulphur and gypsum (AM 64.187-195, Mindat, HOM).
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