| Tinaksite | |
|---|---|
 Tinaksite (brown) and associated charoite (lilac). | |
| General | |
| Category | Silicate mineral |
| Formula | K2Na(Ca,Mn2+)2TiO[Si7O18(OH)] |
| IMA symbol | Tnk [1] |
| Strunz classification | 9.DG.75 |
| Crystal system | Triclinic |
| Crystal class | Pinacoidal (1) (same H-M symbol) |
| Space group | P1 |
| Identification | |
| Color | Pink, pale yellow, light brown |
| Crystal habit | Fibrous, crystalline or prismatic, crystalline, or radial, crystalline |
| Cleavage | Perfect in one direction, indistinct in one direction |
| Mohs scale hardness | 6 |
| Luster | Vitreous to glassy |
| Streak | White |
| Diaphaneity | Transparent to translucent |
| Specific gravity | 2.82 |
| Optical properties | Biaxial (+) |
| Refractive index | nα = 1.593 nβ = 1.621 nγ = 1.666 |
| Birefringence | δ = 0.073 |
| References | [2] [3] [4] |
Tinaksite (chemical formula K2Na(Ca,Mn2+)2TiO[Si7O18(OH)]) [3] is a mineral found in northern Russia. Tinaksite can be grayish-white, yellowish, orange, or brown, [2] and it is often found in charoite. [5] Its name is derived from its composition: titanium (Ti), sodium (Na) potassium (K) and silicon (Si). The International Mineralogical Association first recognized tinaksite as a mineral in 1965.