Formula: Mn2+3Fe3+2(SiO4)3
Nesosilicate, garnet group, manganese-bearing mineral
A complete solid solution exists among calderite, andradite and spessartine.
Crystal System: Isometric
Specific gravity: 4.05 meaasured, 4.07 calculated
Streak: White
Colour: Dark reddish brown to dark yellowish, brown-yellow
Common impurities: Ti, Mg

Metamorphic environments

End member calderite is stable only at high pressure, greater than 22 GPa, and low temperature, and the pure end member does not occur in nature. Calderitic andradite is found in high pressure metamorphic iron and manganese-rich quartzite and chert, also in metamorphosed manganese-silicate-oxide and silicate-carbonate rocks, and in areas of subduction zone metamorphism (Dana).

At the Wabush iron formation, Labrador, Canada (one of two co-type localities), calderite occurs in an iron formation associated with pyrolusite, aegirine, rhodonite, hematite, rhodochrosite, quartz and kutnohorite (HOM).

At Otjosondu, Omatako, Namibia, calderite occurs in a manganese deposit (HOM).

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