Constituent
- Name
- Alunite
- IMA name
- Alunite
- Class
- non-silicate mineral
- Compound type
- sulfate
- Relevance
- main - major
- Arrangement
- in multi-phases
- Mass fraction
- 0.15 $\pm$ 0.1
- Formula
- $KAl_3(SO_4)_2(OH)_6$
- Chemical formula
- KAl3(SO4)2(OH)6
- Elemental formula
- (K+) Al3 S2 O4 (O-)10 H6
- Isotope mixture type
- terrestrial abundance
- Oxides
-
Formula $K_{2}O$ $Al_{2}O_{3}$ $H_{2}O$ $SO_{3}$ Mass fraction (%) 11.37 36.92 13.05 38.66
Strunz
- Class
- sulfates - chromates - molybdates - tungstates (07)
- Division
- sulfates (selenates, etc.) with additional anions, without H2O (07.B)
- Family
- with medium-sized and large cations (07.BC)
- Code
- 07.BC.10
Dana
- Major class
- sulfates, chromates, selenates (VI)
- Class
- anhydrous sulfates containing hydroxyl or halogen (30)
- Type
- where (A B)2 XO4 Zq (30.02)
- Group
- Alunite group (Alunite Subgroup) (30.02.04)
- Code
- 30.02.04.01
- Phase type
- crystalline
- Crystal system
- trigonal
- Crystal class
- ditrigonal-pyramidal
- Crystal class symbol
- 3m (C3v)
- Crystal spacegroup
- R3m
- Molar mass
- 414.21 $g/mol$
- Density
- 2.59 - 2.9 $g/cm^3$
- Refringence type
- uniaxial
- Refringence sign
- positive
- Birefringence
- 0.020
- Refraction index $n_{\alpha}$
- 1.572
- Refraction index $n_{\beta}$
- 1.592
- Color
- white, gray, yellowish gray, reddish gray, yellowish white
- Diaphaneity
- transparent to translucent
- Luster
- vitreous