Formula | Na[NaCa](Mg; Fe 2+)5Si8O22(OH)2 |
Origin | Koksha Valley (Afghanistan) |
Description | idiomorphic, elongated, transparent richterite crystal |
Classification (Lapis) | Amphiboles |
Crystal System | monoclinic |
Hardness | 5,0 – 6,0 |
Colour | Brown, yellow, green, brownish red; colorless to pale yellow in thin section |
Streak | white or grayish |
Luminescence | yes |
Luster | vitreous |
Transparency (Opacity) | transparent to translucent |
Cleavage | perfect |
Fracture | uneven |
Magnetism | negative |
Geological Setting | Commonly in contact metamorphosed limestones; in alkalic igneous rocks and carbonatites. |
Specific Gravity | 3,1 g/cm3 |