Ankerite
| Formula | Ca(Fe2+,Mg,Mn2+)(CO3)2 |
| Origin | Grisons (Switzerland) |
| Description | Ankerite on quartz |
| Classification (Lapis) | Carbonates |
| Crystal System | trigonal |
| Hardness | 3,5-4,0 |
| Colour | brown, yellow, white; colorless in transmitted light |
| Streak | white |
| Luminescence | |
| Luster | vitreous to pearly |
| Transparency (Opacity) | translucent |
| Cleavage | perfect |
| Fracture | subconchoidal |
| Magnetism | negative |
| Geological Setting | formed in low-grade metamorphosed ironstones and sedimentary banded iron formations; in carbonatites; authigenic, diagenetic, or the product of hydrothermal alteration of carbonate sediments and in hydrothermal sulfide veins |
| Specific Gravity | 3,11 g/cm3 |
