Constituent
- Name
- Orthoclase
- IMA name
- Orthoclase
- Class
- silicate mineral
- Compound type
- tektosilicate
- Comments
- Dimorphous with Microcline
- Relevance
- main - major
- Arrangement
- heterogeneous in multi-phases
- Mass fraction
- 10.41
- Formula
- $KAlSi_3O_8$
- Chemical formula
- KAlSi3O8
- Elemental formula
- K Al Si3 O8
- Isotope mixture type
- terrestrial abundance
- Composition comments
- Common replacements: Na, Ba, Ca - Common impurities: Fe, Rb
- Oxides
-
Formula $K_{2}O$ $Na_{2}O$ $BaO$ $CaO$ $Al_{2}O_{3}$ $SiO_{2}$ Mass fraction (%) 16.92 18.32 64.76
Strunz
- Class
- silicates (09)
- Division
- tektosilicate without zeolitic H2O (09.F)
- Family
- Tektosilicates without additional non-tetrahedral anions, (Al,B):Si = 1:1 (09.FA)
- Code
- 09.FA.30
Dana
- Major class
- silicates (VIII)
- Class
- tectosilicate Al-Si framework (76)
- Type
- with Al-Si frameworks (76.01)
- Group
- K (Na,Ba) feldspars (76.01.01)
- Code
- 76.01.01.01
- Phase type
- crystalline
- Crystal system
- monoclinic
- Crystal class
- prismatic
- Crystal class symbol
- 2/m (C2h)
- Crystal spacegroup
- C2/m
- Texture
- polycrystalline
- Molar mass
- 278.33 $g/mol$
- Density
- 2.56 $g/cm^3$
- Refringence type
- biaxial
- Refringence sign
- negative
- Birefringence
- 0.0050 - 0.0060
- Refraction index $n_{\alpha}$
- 1.518
- Refraction index $n_{\beta}$
- 1.522
- Refraction index $n_{\gamma}$
- 1.523 - 1.524
- Dispersion V
- relatively strong
- Color
- colorless, greenish, grayish yellow, white, pink
- Diaphaneity
- transparent to translucent
- Luster
- vitreous