Terlinguaite
| Terlinguaite | |
|---|---|
Terlinguaite, collected from Mariposa Mine, Terlingua District, Brewster County, Texas, United States | |
| General | |
| Category | Halide mineral |
| Formula | Hg4+3Hg2+Cl2O2 |
| IMA symbol | Tlg |
| Strunz classification | 3.DD.20 |
| Crystal system | Monoclinic |
| Crystal class | Prismatic (2/m) (same H-M symbol) |
| Space group | C2/c |
| Unit cell | a = 19.51 Å, b = 5.91 Å c = 9.47 Å; β = 143.81°; Z = 4 |
| Identification | |
| Color | Sulfur-yellow, greenish yellow, brown |
| Crystal habit | Aggregates of equant to elongated crystals, powdery, massive |
| Cleavage | Perfect on [101] |
| Tenacity | Brittle |
| Mohs scale hardness | 2.5 |
| Luster | Brilliant adamantine |
| Streak | Lemon-yellow, turning olive-green |
| Diaphaneity | Transparent to translucent |
| Specific gravity | 9.22 |
| Optical properties | Biaxial (-) |
| Refractive index | nα = 2.350 nβ = 2.640 nγ = 2.660 |
| Birefringence | δ = 0.310 |
| Pleochroism | Weak, green and yellow |
| 2V angle | Measured: 20° |
| Alters to | turns olive-green on exposure to light |
| References | |
Terlinguaite is the naturally occurring mineral with formula Hg4+3Hg2+Cl2O2. It is formed by the weathering of other mercury-containing minerals. It was discovered in 1900 in the Terlingua District of Brewster County, Texas, for which it is named. Its color is yellow, greenish yellow, brown, or olive green.