Shandite
Shandite is a sulfide mineral with chemical formula: Ni3Pb2S2. It was discovered in 1950 and named after Scottish petrologist, Samuel James Shand (1882–1957). It is characterized by a metallic luster and a brass-yellow color. It has a specific gravity of 8.92, and a Mohs hardness value of 4. Shandite is commonly found as an inclusion in other minerals such as serpentine.
| Shandite | |
|---|---|
| General | |
| Category | Sulfide mineral |
| Formula (repeating unit) | Ni3Pb2S2 |
| Strunz classification | 2.BE.15 |
| Crystal system | Trigonal |
| Crystal class | Hexagonal scalenohedral (3m) H-M symbol (3 2/m) |
| Space group | R3m |
| Unit cell | a = 5.59 Å, c = 13.57 Å; Z = 3 |
| Identification | |
| Formula mass | 654.60 g/mol |
| Color | Brass yellow, cream-white in polished section |
| Crystal habit | Generally found as an inclusion |
| Cleavage | {1011} Perfect |
| Mohs scale hardness | 4 |
| Luster | Metallic |
| Diaphaneity | Opaque |
| Specific gravity | 8.72 |
| Birefringence | Strong, dark blue-gray |
| Pleochroism | Distinct |
| References | [1][2][3] |
Its crystal system is trigonal hexagonal scalenohedral with symbol 32/m. It belongs to the space group R3m. Shandite is an anisotropic mineral, which means it has different properties when being viewed from different directions. In cross-polarized light it appears as gray blue or yellow-brown colors. It also has very distinct relief, which means it stands out against its mounting medium and can be easily seen. It has an index of refraction of 1.54, which is the measure of the speed of light through the substance. In plane polarized light, shandite has a creamy white color and distinct pleochroism, which is the property that makes it appear to be different colors at different angles. It has strong birefringence, which is the decomposition of light into two rays, and appears dark blue and gray.