Microcline

Formula : K(AlSi3)O8

Space group: 
Triclinic - Pinacoidal H-M Symbol ( 1) Space Group: C1
Dana class: 
76.1.1.5 (76) Tectosilicate Al-Si Framework (76.1) with Al-Si frameworks (76.1.1)K (Na,Ba) feldspars
High temperature: 
At 400 degrees C or less, microcline is the stable structure for KAlSi3O8.
Geological context: 
Dimorphous with orthoclase. Common in plutonic felsic rocks, as granites, granite pegmatites, syenites; in metamorphic rocks of the greenschist and amphibolite facies; in hydrothermal veins. A detrital component in sedimentary rocks and as authigenic overgrowths.

Dernière mise à jour le 11.06.2018

THERMODYNAMICS

Individual properties (298.15 K)
M
g·mol-1
cm3·mol-1
ΔGºf
J·mol-1
ΔHºf
J·mol-1
J·mol-1·k-1
CP
J·mol-1·K-1
278.332 108.741 -3748993 -3974340 214.200 202.13
Reaction properties

Microcline + 4H+ + 4H2O ⇌ Al+3 + K+ + 3H4SiO4

298.15 K, 1 bar log10K: 0.04 ΔH°r: -56463 J·mol-1
T(°C) 0 25 60 100 150 200 250 300
log10K 0.95 0.04 -0.99 -1.94 -2.90 -3.74 -4.55 -5.40