orthoclase feldspar
81Phonolite — Aegirine phonolite. Dark prismatic minerals are aegirine phenocrysts. Phonolite is a rare igneous, volcanic (extrusive) rock of intermediate (between felsic and mafic) composition, with aphanitic to porphyritic texture. The name phonolite comes… …
82Stone Mountain — This article is about Stone Mountain in Georgia, USA. For other uses, see Stone Mountain (disambiguation). Infobox Mountain Name = Stone Mountain Photo = Stonemtn2.jpg Caption = Overview of Stone Mountain Elevation = convert|1683|ft|m|0 Location …
83Bostonite — Bostonite, in petrology, is a fine grained, pale colored, grey or pinkish intrusive rock, which consists essentially of alkali feldspar (orthoclase, perthite, anorthoclase, and albite). Some samples may contain a small amount of interstitial… …
84Metamorphic facies — Eclogite Blueschist Greenschist Prehnite Pumpellyite …
85monzonite — monzonitic /mon zeuh nit ik/, adj. /mon zeuh nuyt /, n. any of a group of granular igneous rocks having approximately equal amounts of orthoclase and plagioclase feldspar, intermediate in composition between syenite and diorite. [1880 85; < G… …
86sunstone — /sun stohn /, n. a reddish variety of oligoclase feldspar, used as a gem, having a red and bright yellow play of color. [1350 1400; ME; see SUN, STONE] * * * ▪ mineral a gemstone variety of feldspar that has minute platelike inclusions of… …
87Some typical occurrences of the rock-forming feldspars — ▪ Table Some typical occurrences of the rock forming feldspars Potassium feldspars* sanidine potassium rich volcanic rocks and near surface minor intrusions e.g., rhyolites, trachytes, and high temperature contact metamorphic rocks orthoclase… …
88Bayfield group — The Bayfield group is a quartz sandstone found in Wisconsin along the Lake Superior coast.[1] It is named for the village of Bayfield, Wisconsin,[2] but was once known as Western Lake Superior Sandstone.[1] Prior to the 1900s, Bayfield group… …
89Anorthoclase — A*nor tho*clase, n. [Gr. ? priv. + orthoclase.] (Min.) A feldspar closely related to orthoclase, but triclinic. It is chiefly a silicate of sodium, potassium, and aluminium. Sp. gr., 2.57 2.60. [Webster 1913 Suppl.] || …
90Monzonite — Photomicrograph of thin section of monzonite (in cross polarised light) …
