In high-temperature sodic volcanic and hypabyssal rocks.
Valid Species (Pre-IMA) 1885
Rather abundant worldwide. Some localities for well-characterized material include: on Pantelleria and Ustica Islands, Italy. At Larvik, Norway. From Berkum, North Rhine-Westphalia, Ge
Link to MinDat.org Location Data.
From the Greek for "oblique" and "fracture," descriptive of the cleavage