Khinite

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Khinite
General
CategoryCategory:Tellurate minerals
Formula
(repeating unit)
PbCu3TeO6(OH)2
Strunz classification4.FD.30
Dana classification33.1.3.1
Crystal systemOrthorhombic
Unit cellKhinite-4O:
a = 5.740 Å,
b = 9.983 Å,
c = 23.960 Å, Z = 8
Khinite-3T (parakhinite):
a = 5.753 Å,
c = 17.958 Å, Z = 3
Identification
ColorDark green - Bottle green
Crystal habitDipyramidal or curved crystals
Cleavage{001} fair
TenacityBrittle
Mohs scale hardness3.5
LusterVitreous
StreakGreen
DiaphaneitySemitransparent
Density6.5-7.0 (measured) 6.69 (calculated)
Optical propertiesBiaxial (+) (khinite) Uniaxial (-) (parakhinite)
Birefringenceδ = 0.055
PleochroismYellow green - emerald green
2V angle20o
Ultraviolet fluorescenceNone
FusibilityFuses readily to a brown slag
SolubilitySoluble in cold acids
Common impuritiesCa
References[1][2][3][4][5][6]

Khinite is a rare tellurate mineral with the formula Pb2+Cu2+3TeO6(OH)2[1][2][3] It crystallizes in the orthorhombic system and has a bottle-green colour. It is often found as dipyramidal, curved or corroded crystals no more than 0.15 mm in size.[4] The tetragonal dimorph of khinite is called parakhinite.

Occurrence and name[edit]

Both khinite and parakhinite were first identified in 1978 in the Old Guard Mine (Royal Guard Mine), Tombstone District, Cochise County, Arizona, US They were named after Ba-Saw Khin, a Burmese-American mineralogist.[1] They are often found together with tenorite, quetzalcoatlite, quartz, gold, dugganite, chrysocolla, chlorargyrite, bromargyrite, xocomecatlite, and tlapallite.[1][4] Khinite and parakhinite are found in multiple mines across Mexico and the USA.

Parakhinite[edit]

Parakhinite crystallizes in the tetragonal system. Khinite and parakhinite are also called khinite-4O and khinite-3T, respectively. Khinite and parakhinite are identical in colour and many other properties, like reactivity. They do differ in optical properties: Khinite is biaxial (+), while parakhinite is uniaxial (-). They also have different unit cells.[1][3][5][6]

References[edit]

  1. ^ a b c d "Khinite: Khinite mineral information and data". www.mindat.org. Retrieved 2016-10-28.
  2. ^ Barthelmy, Dave. "Khinite Mineral Data". www.webmineral.com. Retrieved 2016-10-28.
  3. ^ a b Williams, S.A. (1978). "Khinite, parakhinite, and dugganite, three new tellurates from Tombstone. Arizona" (PDF). American Mineralogist. 63: 1016–1019.
  4. ^ a b "Handbook of mineralogy, Khinite" (PDF).
  5. ^ Cooper, M. A.; Hawthorne, F. C.; Back, M. E. (2008). "The crystal structure of khinite and polytypism in khinite and parakhinite". Mineralogical Magazine. 72 (3): 763–770. doi:10.1180/minmag.2008.072.3.763.
  6. ^ Hawthorne, F. C.; Cooper, M. A.; Back, M. E. (2009). "KHINITE-4O [= KHINITE] AND KHINITE-3T [= PARAKHINITE]". The Canadian Mineralogist. 47 (2): 473–476. doi:10.3749/canmin.47.2.473.