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Formula: CaB2Si2O8
Sorosilicate (Si2O7 groups)
Crystal System: Orthorhombic
Specific gravity: 2.93 to 3.02 measured, 2.99 calculated
Hardness: 7 to 7½
Streak: White
Colour: Colourless, yellowish to dark brown, pink
Solubility: Soluble in acids (Dana)
Common impurities:Fe,Mn,Al,Mg,Sr,Na
Environments:
Plutonic igneous environments
Pegmatites
Metamorphic environments
Hydrothermal environments
Evaporites
Danburite occurs in hypothermal (high temperature) veins, where it is associated with
quartz,
cassiterite,
fluorite and
orthoclase. It occurs in moderate to low temperature and low iron-bearing
contact metamorphic rocks, where it is associated with
andradite,
wollastonite and sulphides.
Other associated minerals include titanite,
axinite, tourmaline,
mica, grossular,
albite, apophyllite,
stilbite,
dolomite,
calcite and gypsum
(HOM)
Danburite occurs in granite and metamorphosed carbonates and
evaporites,
in skarn, in marine
salt deposits and in alpine crevices.
Localities
At Zechstein, Germany, danburite occurs with anhydrite
(Dana).
At the Toroku mine, Takachiho, Nishiusuki District, Miyazaki Prefecture, Japan, danburite is associated with
axinite
(Dana).
At the Anjanabonoina pegmatites, Ambohimanambola, Betafo, Vakinankaratra, Madagascar, the
pegmatite dikes are emplaced in a complex environment of
paragneiss, marble and
orthogneiss, of medium metamorphic grade. Abundant
tourmalinisation extensively affected
schist and quartzite
units. Veins of quartz,
dravite-schorl and danburite are
locally present in metasedimentary rocks close to the pegmatites
(Mindat).
At Charcas, San Luis Potosi, Mexico,
At Piz Valatscha, Val Medels, Uri, Graubunden, Switzerland, danburite occurs with
smoky quartz in gneiss
(Dana).
At the type locality, Danbury, Fairfield County, Connecticut, USA, danburite occurs in metamorphosed
limestone
(Dana).
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