තලාතු මිනිරං
| තලාතු මිනිරං | |
|---|---|
 biotite: Topotype deposit (Image width: 2.5 mm) | |
| General | |
| Category | Dark mica series |
| රසායනික සූත්රය | K(Mg,Fe)3(AlSi3O10)(F,OH)2 |
| Identification | |
| අණුක ස්කන්ධය | 433.53 g |
| පාට / පැහැය | Dark brown, greenish-brown, blackish-brown, yellow, white |
| Crystal habit | Massive to platy |
| Crystal system | Monoclinic (2/m) Space Group: C 2/m |
| Twinning | Common on the [310], less common on the {001} |
| Cleavage | Perfect on the {001} |
| Fracture | Micaceous |
| Tenacity | Brittle to flexible, elastic |
| Mohs scale hardness | 2.5–3.0 |
| Luster | Vitreous to pearly |
| Streak | White |
| Diaphaneity | Transparent to translucent to opaque |
| Specific gravity | 2.7–3.1 |
| ඝනත්වයy | 2.8–3.4 |
| Optical properties | Biaxial (-) |
| Refractive index | nα = 1.565–1.625 nβ = 1.605–1.675 nγ = 1.605–1.675 |
| Birefringence | δ = 0.03–0.07 |
| Pleochroism | Strong |
| Dispersion | r < v (Fe rich); r > v weak (Mg rich) |
| Ultraviolet fluorescence | None |
| References | [1][2][3] |