Montroydite

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Montroydite
Montroydite-mf17c.jpg
Vein of dark red montroydite and orange kleinite in a matrix of white calcite
General
Category Oxide mineral
Formula HgO
IMA symbol Mtyd [1]
Strunz classification 4.AC.15
Crystal system Orthorhombic
Crystal class Dipyramidal (mmm)
H-M Symbol: (2/m 2/m 2/m)
Unit cell a = 5.52 Å, b = 6.6 Å, c = 3.52 Å; Z=4
Identification
ColorDeep red, brownish red to brown
Crystal habit Long prismatic, equant, rarely flattened; striated; massive to vermicular clusters
Cleavage Perfect {010}
Tenacity Sectile
Mohs scale hardness1.5 - 2.0
Luster Sub-adamantine, vitreous
Streak Yellow brown
Diaphaneity Transparent to translucent
Specific gravity 11.23
Optical propertiesBiaxial (+)
Refractive index nα = 2.370 nβ = 2.500 nγ = 2.650
Birefringence δ = 0.280
Pleochroism Deep red-orange to yellowish brown (visible in thick sections)
2V angle Large
References [2] [3]

Montroydite is the mineral form of mercury(II) oxide with formula HgO. It is a rare mercury mineral. It was first described for an occurrence in the mercury deposit at Terlingua, Texas and named for Montroyd Sharp who was an owner of the deposit. [2]

Montroydite occurs in mercury deposits of hydrothermal origin. Associated minerals include: native mercury, cinnabar, metacinnabar, calomel, eglestonite, terlinguaite, mosesite, kleinite, edgarbaileyite, gypsum, calcite and dolomite. [3]

References

  1. Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi: 10.1180/mgm.2021.43 . S2CID   235729616.
  2. 1 2 Mindat.org
  3. 1 2 "Handbook of Mineralogy" (PDF). Archived from the original (PDF) on 2022-07-02. Retrieved 2017-08-04.