In calcite or quartz veins of apparently low temperature, late stage hydrothermal origin. Also in silicified, recrystallized metamorphic rock.
IMA Status:
Valid Species (Pre-IMA) 1866
Locality:
In the Elizabeth mine, Oravita (Oravicza), Romania. From the Silverfields mine, Cobalt, and the Siscoe mine, Miller Lake, Gowganda, Ontario, Canada. Link to MinDat.org Location Data.
Name Origin:
From the Greek for "other", and "to break," because its cleavage was believed to be different from marcasite, which it resembles.
Chemical Formula: 