- a common white or pink mineral of the feldspar group, KAlSi3O8, having two good cleavages at right angles, and found in silica-rich igneous rocks: used in the manufacture of porcelain.
Origin of orthoclase
1840–50; ortho- + -clase < Greek klásis cleavage, breaking
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
Examples from the Web for orthoclase
In syenite and greenstone it occurs more commonly than orthoclase.Geology
If the initial composition of the magma is represented by a point between the two eutectic points, orthoclase will separate first.
This curve would represent the conditions under which orthoclase is in equilibrium with the molten magma.
The china-clay rocks of Cornwall and Devon are granites in which the orthoclase has become kaolinized.
The turbidity of orthoclase is usually due to partial kaolinization.
- a white to pale yellow, red, or green mineral of the feldspar group, found in igneous, sedimentary, and metamorphic rocks. It is used in the manufacture of glass and ceramics. Composition: potassium aluminium silicate. Formula: KAlSi 3 O 8 . Crystal structure: monoclinic
- A white to yellowish red monoclinic mineral of the potassium feldspar group that forms from medium- to low-temperature magmas. Chemical formula: KAlSi3O8.
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