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Formula: MgB4O5(OH)4.7H2O
Hydrated tetraborate
Crystal System: Triclinic
Specific gravity: 1.706 measured, 1.703 calculated
Hardness: 2½
Colour: Colourless
Luminescence: Not fluorescent under UV
Environments
Localities
The type locality is the Qaidam salt lake, Da Qaidam, Haixi Mongol and Tibetan Autonomous Prefecture, Qinghai, China.
The Qinghai-Tibet Plateau has rich salt lake resources, especially boron
resources. These are of two types, the solid type and the liquid type; the amount of liquid
boron resources is predominant, but the most utilised are the
solid boron resources
(Acta Geologica Sinica 44.351-356).
Minerals associated with hungchaoite include ulexite,
hydroboracite, szaibélyite
and gypsum
(HOM).
At the Furnace Creek Mining District, Inyo County, California, USA, hungchaoite occurs with
ginorite, mcallisterite,
sborgite, sassolite,
nobleite, ulexite, and, where
gypsum and ulexite are abundant, with
kurnakovite, inderite and
mcallisterite in surficial matrix as products from weathered
colemanite and priceite veins.
Although the rocks enclosing the priceite and
colemanite veins are of late Tertiary age (66 to 2.6 million years ago),
the hungchaoite and associated minerals around the veins are Holocene (present epoch, beginning around
11,000 years ago) and still form in the present desert environment. Boron of
the hungchaoite, which was released from weathered priceite and
colemanite, apparently migrated much earlier from bedded
ulexite in the ore zone
(AM 64.369-375).
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