Knowra Microcline Microcline Microcline is a potassium-rich feldspar with a triclinic crystal structure, common in granites and pegmatites. Its crystals often display cross-hatched twinning.
Feldspar : Feldspars are a group of rock-forming aluminosilicate minerals containing potassium, sodium, or calcium. Microcline belongs to this abundant mineral family.
Aluminium-silicon ordering : Aluminium-silicon ordering is the arrangement of aluminium and silicon among sites in a mineral’s crystal framework. Greater ordering distinguishes microcline from higher-temperature potassium feldspars.
Orthoclase : Orthoclase is a monoclinic potassium feldspar with less aluminium-silicon ordering than microcline. Its symmetry and degree of ordering distinguish it from microcline.
Granite : Granite is a coarse-grained igneous rock composed chiefly of quartz, feldspar, and mica or related minerals. Microcline is a common potassium feldspar in many granites.
Alkali feldspar : Alkali feldspars are feldspars dominated by potassium and sodium rather than calcium. Microcline is the potassium-rich member of this compositional series.
Feldspar phase diagram : A feldspar phase diagram shows stable mineral compositions and structures as temperature and composition change. It describes the temperature-dependent relations among potassium feldspar polymorphs.
Sanidine : Sanidine is a high-temperature monoclinic potassium feldspar with relatively disordered aluminium and silicon. It contrasts with microcline’s low-temperature, ordered triclinic structure.
Pegmatite : Pegmatite is an exceptionally coarse-grained igneous rock, often enriched in uncommon minerals and large crystals. Microcline can form large, well-developed crystals in pegmatites.
Potassium feldspar : Potassium feldspar is a feldspar composition dominated by potassium, including microcline, orthoclase, and sanidine. Microcline is one of the principal potassium-feldspar polymorphs.
Perthite : Perthite is an intergrowth of sodium-rich and potassium-rich feldspar formed by unmixing in a solid crystal. Microcline commonly hosts sodium-rich lamellae produced during cooling.
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