Terlinguaite

Terlinguaite
Terlinguaite, collected from Mariposa Mine, Terlingua District, Brewster County, Texas, United States
General
Category	Mineral
Formula (repeating unit)	Hg2ClO
Strunz classification	3.DD.20
Crystal system	Monoclinic
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 symmetry	Monoclinic - prismatic H-M symbol: (2/m) Space group: C 2/c
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

1. Handbook of Mineralogy
2. Mindat.org
3. Webmineral data
4. Hillebrand, W. F.; W. T. Schaller (1907). "Art. XXVI. "The Mercury Minerals from Terlingua, Texas: Kleinite, Terlinguaite, Eglestonite, Montroydite, Calomel, Mercury"". The American Journal of Science (139): 259–274. Retrieved 2009-05-21.