Danburite

danburite

axinite-(Mg)

andradite

wollastonite

Images

Formula: CaB2Si2O8
Sorosilicate (Si2O7 groups)
Specific gravity: 2.9 to 3.0
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, is associated with calcite, datolite and nifontovite (Dana). Quartz pseudomorphs after danburite have been found here (KL p250, R&M 95.3.275).

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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