Amethyst vs Fluorite
Both can be purple, but hardness and cleavage differ sharply.
| Property | Amethyst | Fluorite |
|---|---|---|
| Category | minerals | minerals |
| Group | Silicate | Halide |
| Class | Silicates | Halides |
| Chemical formula | SiO2 | CaF2 |
| Crystal system | Trigonal | Isometric |
| Mohs hardness | 7 | 4 |
| Specific gravity | 2.65 | 3 – 3.3 |
| Colour | Purple | Purple, green, blue, yellow, colourless |
| Streak | White | White |
| Luster | Vitreous | Vitreous |
| Transparency | Transparent to translucent | Transparent to translucent |
| Formation environment | Hydrothermal veins and geodes | Hydrothermal veins |
| Common uses | Gemstone and ornamental stone | Flux, optics, collector specimens |