Terlinguaite

Terlinguaite
General
Category Mineral
Formula
(repeating unit)
Hg2ClO
Strunz classification 3.DD.20
Crystal symmetry Monoclinic prismatic
H-M symbol: (2/m)
Space group: C 2/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
Crystal system Monoclinic
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 [1][2][3]

Terlinguaite is the naturally occurring mineral with formula Hg2ClO. It is formed by the weathering of other mercury-containing minerals. Discovered in 1900 in the Terlingua District of Brewster County, Texas for which it is named.[4] Its color is yellow, greenish yellow, brown or olive green.

References