Zunyite

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Zunyite
Zunyite-199876.jpg
Sharp, pyramids of brown-red zunyite from Silver City, Tintic District, East Tintic Mountains, Juab County, Utah, US (size: 5.5 x 5 x 3.5 cm)
General
CategorySorosilicates
Formula
(repeating unit)
Al13Si5O20(OH,F)18Cl
IMA symbolZnu[1]
Strunz classification9.BJ.55
Crystal systemIsometric
Crystal classHextetrahedral (43m)
H-M symbol: (43m)
Space groupF43m
Unit cella = 13.8654 - 13.8882 Å; Z = 4
Identification
ColorGrayish white, flesh-red; colorless in thin section
Crystal habitCrystalline - occurs as well-formed fine sized crystals
TwinningOn {111}, contact and penetration
CleavageGood on {111}
FractureUneven
TenacityBrittle
Mohs scale hardness7
LusterVitreous
StreakWhite
DiaphaneityTransparent to translucent with inclusions
Specific gravity2.874(5) (meas.) 2.87 - 2.90 (calc.)
Optical propertiesIsotropic
Refractive indexn = 1.592 - 1.600
Other characteristicsMay fluoresce red under UV
References[2][3][4]

Zunyite is a sorosilicate mineral, Al13Si5O20(OH,F)18Cl, composed of aluminium, silicon, hydrogen, chlorine, oxygen, and fluorine.

Occurrence[edit]

Glassy, translucent, gray-tan, pseudohexagonal zunyite crystals on a milky quartz matrix. From the Big Bertha Mine, Dome Rock Mountains, La Paz County, Arizona (size: 3.3 x 3.2 x 2.8 cm))

Zunyite occurs in highly aluminous shales and hydrothermally altered volcanic rocks. It occurs in association with pyrophyllite, kaolinite, alunite, diaspore, rutile, pyrite, hematite and quartz.[2]

It was discovered in 1884, and named for its discovery site, the Zuni mine in the Silverton District, San Juan County, Colorado.[3]

References[edit]

  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. ^ a b Handbook of Mineralogy
  3. ^ a b Mindat.org
  4. ^ Web Mineral