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Feldspathic refers to materials that contain feldspar. The alternate spelling, felspar, has fallen out of use. The term 'felsic', meaning light coloured minerals such as quartz and feldspars, is an acronymic word derived from feldspar and silica, unrelated to the obsolete spelling 'felspar'.
Granite (/ ˈ ɡ r æ n ɪ t / GRAN-it) is a coarse-grained intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase.It forms from magma with a high content of silica and alkali metal oxides that slowly cools and solidifies underground.
Larvikite is prized for its high polish and the labradorescence of its feldspar crystals, and is used as dimension stone, often cladding the facades of commercial buildings and corporate headquarters. [1] It is known informally as Blue Pearl Granite, although this is not an accurate description.
Feldspar is a group of rock-forming minerals, including: Alkali feldspar; Alkali feldspar granite; Potassium feldspar; Feldspar may also refer to: A community in Tay Valley, Ontario, Canada; USS Feldspar (IX-159), a concrete barge; Craig Feldspar, a character in the American television comedy series Malcolm in the Middle
Rapakivi granite is an igneous intrusive rock and variant of alkali feldspar granite. It is characterized by large, rounded crystals of orthoclase each with a rim of oligoclase (a variety of plagioclase). Common mineral components include hornblende and biotite. The name has come to be used most frequently as a textural term where it implies ...
Quartzolite or silexite is an intrusive igneous rock, in which the mineral quartz is more than 90% of the rock's felsic mineral content, with feldspar at up to 10%. [ 1 ] : 135 [ 2 ] Typically, quartz forms more than 60% of the rock, [ 3 ] the rest being mostly feldspar although minor amounts of mica or amphibole may also be present. [ 2 ]
The feldspathoids are a group of tectosilicate minerals which resemble feldspars but have a different structure and much lower silica content. They occur in rare and unusual types of igneous rocks, and are usually not found in rocks containing primary quartz.
The most common mineral assemblage of granulite facies consists of antiperthitic plagioclase, alkali feldspar containing up to 50% albite and Al 2 O 3-rich pyroxenes. Transition between amphibolite and granulite facies is defined by these reaction isograds: amphibole → pyroxene + H 2 O biotite → K-feldspar + garnet + orthopyroxene + H 2 O.