Crossite - Encyclopedia
Class : Silicates
Subclass : Inosilicates
Crystal system : Monoclinique
Chemistry : Na2(Mg,Fe)3(Al,Fe)2Si8O22(OH)2
Rarity : Common
Crossite belongs to the group of sodium amphiboles, within which it constitutes an intermediate term of the glaucophane - riebeckite series. It is an amphibole of regional metamorphic rocks of low temperature and low and high pressure (green schist and glaucophane blue schist facies respectively); it is also present in eclogites. It was named in honor of the American geologist Charles Whitman Cross. Its crystals are often indistinct, and rarely constitute elongated prisms ; generally, crossite forms lamellar, fibrous, granular or bacillary masses, gray to grayish blue in color.
Main photo : Crossite from Voglau, Salzburg, Austria © Matteo Chinellato
Crossite in the World
Twinning
No twins known for this mineral species.
Fakes and treatments
No fakes listed for this mineral species.
Hardness : 6
Density : 3
Fracture : Sub-conchoidal
Streak : White
TP : Translucent to opaque
RI : 1.640 to 1.670
Birefringence : 0.012
Optical character : Biaxial -
Pleochroism : None
Fluorescence : None
Solubility : Insoluble
Magnetism : Paramagnetic
Radioactivity : None