Hemihedrite
| Hemihedrite | |
|---|---|
Red phoenicochroite and orange hemihedrite microcrystals richly cover the matrix | |
| General | |
| Category | Chromate mineral |
| Formula | Pb10Zn(CrO4)6(SiO4)2(F,OH)2 |
| IMA symbol | Hhe |
| Strunz classification | 7.FC.15 |
| Crystal system | Triclinic |
| Space group | P1 (No. 2) |
| Unit cell | a = 9.49, b = 11.44 c = 10.84 [Å]; α = 120.5° β = 92.1°, γ = 55.83°; Z = 1 |
| Identification | |
| Color | Bright orange, henna-brown, to almost black |
| Crystal habit | Euhedral crystals with hemihedral morphology |
| Twinning | Present |
| Mohs scale hardness | 3 |
| Luster | Vitreous |
| Streak | Saffron-yellow |
| Diaphaneity | Translucent to transparent |
| Specific gravity | 6.42 |
| Optical properties | Biaxial (+) |
| Refractive index | nα = 2.105 nβ = 2.320 nγ = 2.650 |
| Birefringence | δ = 0.545 |
| Pleochroism | Feeble, yellow to orange |
| 2V angle | 88° (measured) |
| References | |
Hemihedrite is a rare lead zinc chromate silicate mineral with formula Pb10Zn(CrO4)6(SiO4)2(F,OH)2. It forms a series with the copper analogue iranite.