Zunyite

Zunyite
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
FormulaAl13Si5O20(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

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

  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