Chemistry:Terlinguaite

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Terlinguaite
Calomel, Terlinguaite-222734.jpg
Terlinguaite, collected from Mariposa Mine, Terlingua District, Brewster County, Texas, United States
General
CategoryHalide mineral
Formula
(repeating unit)
Hg2ClO
Strunz classification3.DD.20
Crystal systemMonoclinic
Crystal classPrismatic (2/m)
(same H-M symbol)
Space groupC2/c
Unit cella = 19.51 Å, b = 5.91 Å
c = 9.47 Å; β = 143.81°; Z = 4
Identification
ColorSulfur-yellow, greenish yellow, brown
Crystal habitAggregates of equant to elongated crystals, powdery, massive
CleavagePerfect on [101]
TenacityBrittle
Mohs scale hardness2.5
|re|er}}Brilliant adamantine
StreakLemon-yellow, turning olive-green
DiaphaneityTransparent to translucent
Specific gravity9.22
Optical propertiesBiaxial (-)
Refractive indexnα = 2.350 nβ = 2.640 nγ = 2.660
Birefringenceδ = 0.310
PleochroismWeak, green and yellow
2V angleMeasured: 20°
Alters toturns 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. 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.

References