Pargasite

Pargasite or pargasitic hornblende is a complex inosilicate mineral of the amphibole group. It was first described for an occurrence in Pargas, Finland in 1814 and named for the locality.

Pargasite occurs in high temperature regional metamorphic rocks and in the skarns within contact aureoles around igneous intrusions. It also occurs in andesite volcanic rocks and altered ultramafic rocks.

Pargasite is the main water-storage site in the uppermost mantle; however, it becomes unstable at depths greater than 90 km (56 mi).