Zincoberaunite

Last updated
Zincoberaunite
General
Category Phosphate minerals
Formula ZnFe3+5(OH)5(PO4)4·6H2O
IMA symbol Zbru [1]
Strunz classification 8.DC.27
Crystal system Monoclinic
Crystal class Prismatic (2/m)
(same H-M symbol)
Space group C2/c
Unit cell a = 20.837(2) Å, b = 5.1624(4) Å, c = 19.250(1) Å; β = 93.252(5)°
Identification
ColorLight gray, light greenish yellow
Crystal habit Fiber, capillary or prismatic microcrystals
Mohs scale hardness3–4
Luster VSilky, vitreous
Diaphaneity Translucent
Specific gravity 2.94
Optical propertiesBiaxial (+)
Refractive index nα = 1.745 nβ = 1.760 nγ = 1.770
Birefringence δ = 0.025
2V angle Measured: 80°
References [2]

Zincoberaunite is an iron and zinc phosphate mineral, the Zn analogue of beraunite. It was first described by Chukanov et al. for an occurrence in Hagendorf Sud pegmatite in Germany. [3] Zincoberaunite occurs as a secondary mineral as an alteration product of primary phosphate minerals in granite pegmatites.

Contents

Beraunite crystallizes in the monoclinic crystal system with point group 2/m. Beraunite's formula is Zn Fe3+5(OH)5(PO4)4·4H2O.

Occurrence

Zincoberaunite has been located so far in two localities in the world, the type locality, and Krasno, near Horní Slavkov (Czech Republic). It appears in two paragenesis, as an alteration of other phosphates in pegmatites: in one with jungle, phosphophyllite and mitridatite and in another with flurlite, plimerite, beraunite rich in zinc, schoonerite, parascholzite, robertsite and altered phosphophyllite. However, it is likely that a detailed study of the zinc-rich beraunite specimens will allow locating other localities for the zincoberaunite.

Physical and chemical properties

Zincoberaunite contains Zn instead of ferrous iron. Before it was characterized as an independent species, specimens with a high zinc content had been found, but since the iron content was higher, they had been considered as varieties. In addition to the elements indicated in the formula, it contains small amounts of magnesium and calcium. In the type locality it appears as pale gray capillary microcrystals forming silky-looking aggregates. In a second locality it has been found as prismatic microcrystals with compositional zoning. [4]

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. Mindat.org
  3. Chukanov, N.V., Pekov, I.V., Grey, I.E., Price, J.R., Britvin, S.N., Krzhizhanovskaya, M.G., Kampf, A.R., Dünkel, B., Keck, E., Belakovskiy, D.I., MacRae, C.M. (2017). "Zincoberaunite, ZnFe3+5(PO4)4(OH)5⋅6H2O, a new mineral from the Hagendorf South pegmatite, Germany". Mineralogy and Petrology. 111 (3): 351–361. doi:10.1007/s00710-016-0482-y. S2CID   133425928.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  4. Tvrdý, J., Plášil, J. Škoda, R. (2020). "New crystal-chemical data on zincoberaunite from Krásno near Horní Slavkov (Czech Republic)". Journal of Geosciences. 65: 45–57. doi: 10.3190/jgeosci.296 . S2CID   219082389.{{cite journal}}: CS1 maint: multiple names: authors list (link)