Khinite

Khinite
Dark green Khinite crystals from the type locality (Bird Nest Drift, San Bernardino County, California, United States of America).
General
Category	Tellurate minerals
Formula	PbCu3TeO6(OH)2
IMA symbol	Khn [1]
Strunz classification	4.FD.30
Dana classification	33.1.3.1
Crystal system	Orthorhombic
Unit cell	Khinite-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
Color	Dark green – Bottle green
Crystal habit	Dipyramidal or curved crystals
Cleavage	{001} fair
Tenacity	Brittle
Mohs scale hardness	3.5
Luster	Vitreous
Streak	Green
Diaphaneity	Semitransparent
Specific gravity	6.5–7.0 (measured) 6.69 (calculated)
Optical properties	Biaxial (+) (khinite) Uniaxial (−) (parakhinite)
Birefringence	δ = 0.055
Pleochroism	Yellow green – emerald green
2V angle	20o
Ultraviolet fluorescence	None
Fusibility	Fuses readily to a brown slag
Solubility	Soluble in cold acids
Common impurities	Ca
References

Khinite is a rare orthotellurate mineral with the formula Pb ²⁺ Cu ²⁺₃ Te O ₆(O H)₂. ^{[2] [3] [4]} 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. ^[5] The tetragonal dimorph of khinite is called parakhinite.

Occurrence and name

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. ^[2] They are often found together with tenorite, quetzalcoatlite, quartz, gold, dugganite, chrysocolla, chlorargyrite, bromargyrite, xocomecatlite, and tlapallite. ^{[2] [5]} Khinite and parakhinite are found in multiple mines across Mexico and the USA.

Parakhinite

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. ^{[2] [4] [6] [7]}

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. "Khinite: Khinite mineral information and data". www.mindat.org. Retrieved 2016-10-28.
3. Barthelmy, Dave. "Khinite Mineral Data". www.webmineral.com. Retrieved 2016-10-28.
4. Williams, S.A. (1978). "Khinite, parakhinite, and dugganite, three new tellurates from Tombstone. Arizona" (PDF). American Mineralogist. 63: 1016–1019.
5. "Handbook of mineralogy, Khinite" (PDF).
6. 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. Bibcode:2008MinM...72..763C. doi:10.1180/minmag.2008.072.3.763. S2CID   140537204.
7. Hawthorne, F. C.; Cooper, M. A.; Back, M. E. (2009). "Khinite-4O [= Khinite] and Khinite-3T [= Parakhinite]". The Canadian Mineralogist. 47 (2): 473–476. Bibcode:2009CaMin..47..473H. doi:10.3749/canmin.47.2.473.