| Terlinguaite | |
| Category: | Halide mineral |
| Formula: | Hg2ClO |
| Imasymbol: | Tlg[1] |
| Strunz: | 3.DD.20 |
| System: | Monoclinic |
| Class: | Prismatic (2/m) (same H-M symbol) |
| Symmetry: | C2/c |
| Unit Cell: | a = 19.51 Å, b = 5.91 Å c = 9.47 Å; β = 143.81°; Z = 4 |
| Color: | Sulfur-yellow, greenish yellow, brown |
| Habit: | Aggregates of equant to elongated crystals, powdery, massive |
| Cleavage: | Perfect on [{{overline|1}}01] |
| Tenacity: | Brittle |
| Mohs: | 2.5 |
| Luster: | Brilliant adamantine |
| Streak: | Lemon-yellow, turning olive-green |
| Diaphaneity: | Transparent to translucent |
| Gravity: | 9.22 |
| Opticalprop: | Biaxial (-) |
| Refractive: | nα = 2.350 nβ = 2.640 nγ = 2.660 |
| Birefringence: | δ = 0.310 |
| Pleochroism: | Weak, green and yellow |
| 2V: | Measured: 20° |
| Alteration: | turns olive-green on exposure to light |
| References: | [2] [3] [4] |
Terlinguaite is the naturally occurring mineral with formula Hg2ClO. 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.[5] Its color is yellow, greenish yellow, brown, or olive green.