Formula | (Mg; Fe 2+)2(Mg; Fe 2+)5Si8O22(OH)2 |
Origin | Heřmanov (Czech Republic) |
Description | Anthophyllite with biotite lens, so-called Hermanover sphere |
Classification (Lapis) | Amphiboles |
Crystal System | orthorhombic |
Hardness | 5,5 – 6,0 |
Colour | Gray, brownish gray, yellowish brown, clove-brown, brownish green, emerald-green; in thin section, colorless to pale green or yellow |
Streak | white or grayish |
Luminescence | none observed |
Luster | vitreous |
Transparency (Opacity) | transparent to translucent |
Cleavage | perfect |
Fracture | |
Magnetism | negative |
Geological Setting | From contact metamorphism of Ca-Mg siliceous sediments; in greenschist facies metamorphics derived from ultrama¯c or magnesium carbonate rocks. |
Specific Gravity | 2,9 g/cm3 |