Fraipontite
Fraipontite | |
---|---|
![]() Pockets of minute pearly white fraipontite crystals with green smithsonite from Laurium, Greece (size: 1.4 x 1.0 x 0.9 cm) | |
General | |
Category | Phyllosilicate |
Formula (repeating unit) | (Zn,Al)3(Si,Al)2O5(OH)4 |
IMA symbol | Fpt[1] |
Strunz classification | 9.ED.15 |
Crystal system | Monoclinic |
Crystal class | Domatic (m) (same H-M symbol) |
Space group | Cm |
Unit cell | a = 5.34, b = 9.21 c = 14.12 [Å]; β = 93.2°; Z = 2 |
Identification | |
Color | Blueish, yellow white light green |
Crystal habit | Fibrous to porcelaneous massive |
Mohs scale hardness | 3.5 – 4 |
Luster | Silky |
Streak | White to pale green |
Diaphaneity | Opaque to translucent |
Specific gravity | 3.08 – 3.10 |
Optical properties | Biaxial (-) |
Refractive index | nα = 1.620 nβ = 1.624 nγ = 1.624 |
Birefringence | δ = 0.004 |
2V angle | Measured: 15° to 20° |
References | [2][3][4] |
Fraipontite is a zinc aluminium silicate mineral with a formula of (Zn,Al)3(Si,Al)2O5(OH)4.[2][3]
It is a member of the kaolinite-serpentine mineral group and occurs as an oxidation product of zinc deposits. It occurs with smithsonite, gebhardite, willemite, cerussite and sauconite.[2]
It was first described in 1927 for an occurrence in Vieille Montagne, Verviers, Liège Province, Belgium.[3] It was named for Julien Jean Joseph Fraipont (1857–1910), and Charles de Fraipont, geologists of Liege, Belgium.[4] In addition to the type locality in Belgium, it has been reported from Tsumeb, Namibia; Laurium, Greece; Swaledale, North Yorkshire, England; the Silver Bill mine, Cochise County, Arizona, the Blanchard Mine, Socorro County, New Mexico and the Mohawk mine, San Bernardino County, California in the US; and from the Ojuela mine, Mapimi, Durango, Mexico.[2]
A synonym of the fraipontite is the zinalsite, which was reported in 1956 for an occurrence in Kazakhstan.[5][6]
References
[edit]- ^ 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.
- ^ a b c d Handbook of Mineralogy
- ^ a b c Mindat.org
- ^ a b Webmineral data for fraipontite
- ^ Zinalsite on Webmineral
- ^ Zinalsite on Mindat
External links
[edit] Media related to Fraipontite at Wikimedia Commons