Ad
related to: k feldspar varieties
Search results
Results From The WOW.Com Content Network
K-feldspar is the final feldspar to crystallize from the magma. [18] [19] Alkali feldspars ... with the variety of ions controlled by the type of feldspar reacting.
Orthoclase, or orthoclase feldspar (endmember formula K Al Si 3 O 8), is an important tectosilicate mineral which forms igneous rock. The name is from the Ancient Greek for "straight fracture", because its two cleavage planes are at right angles to each other. It is a type of potassium feldspar, also known as K-feldspar.
Potassium feldspar refers to a number of minerals in the feldspar group that contain large amounts of potassium in the crystal lattice. Orthoclase (endmember formula K Al Si 3 O 8), an important tectosilicate mineral that forms igneous rock; Microcline, chemically the same as orthoclase, but with a different crystalline structure
Alkali feldspar granite, some varieties of which are called 'red granite', [1] is a felsic igneous rock and a type of granite rich in the mineral potassium feldspar (K-spar). It is a dense rock with a phaneritic texture. The abundance of K-spar gives the rock a predominant pink to reddish hue; peppered with minor amounts of black minerals. [2] [3]
Perthitic textures: antiperthite (1), perthite (2), and mesoperthite (3) Perthite or perthitic texture is used to describe an intergrowth of two feldspars: a host grain of potassium-rich alkali feldspar (near K-feldspar, KAlSi 3 O 8, in composition) includes exsolved lamellae or irregular intergrowths of sodic alkali feldspar (near albite, NaAlSi 3 O 8, in composition).
Moonstone is a sodium potassium aluminium silicate ((Na,K)AlSi 3 O 8) of the feldspar group that displays a pearly and opalescent schiller. [1] [2] An alternative name for moonstone is hecatolite [2] (from goddess Hecate).
Sanidine is the high temperature form of potassium feldspar with a general formula K(AlSi 3 O 8). [2] Sanidine is found most typically in felsic volcanic rocks such as obsidian, rhyolite and trachyte. Sanidine crystallizes in the monoclinic crystal system. Orthoclase is a monoclinic polymorph stable at lower temperatures.
This is the initial stage of K-metasomatism in cataclastically-deformed magmatic plutonic rocks. The breakage happens primarily along grain boundary seals and the K-metasomatism may locally replace rims of zoned plagioclase crystals to form interstitial alkali feldspar and rim myrmekite (see illustration).