orthoclase feldspar
61Micrographic texture — In petrology, micrographic texture is a fine grained intergrowth of quartz and alkali feldspar, interpreted as the last product of crystallization in some igneous rocks which contain high or moderately high percentages of silica. Micropegmatite… …
62granite — granitic /greuh nit ik/, adj. granitelike, adj. /gran it/, n. 1. a coarse grained igneous rock composed chiefly of orthoclase and albite feldspars and of quartz, usually with lesser amounts of one or more other minerals, as mica, hornblende, or… …
63trachyte — trachytic /treuh kit ik/, trachytoid /trak i toyd , tray ki /, adj. /tray kuyt, trak uyt/, n. a fine grained volcanic rock consisting essentially of alkali feldspar and one or more subordinate minerals, as hornblende or mica: the extrusive… …
64Plagioclase — A photomicrograph of a plagioclase crystal under cross polarized light. The plagioclase crystal shows a distinct banding effect called a Polysynthetic twinning. (unknown scale) General Category …
65Syenite — is a coarse grained intrusive igneous rock of the same general composition as granite but with the quartz either absent or present in relatively small amounts ( …
66adularia — /aj euh lair ee euh/, n. Mineral. a sometimes opalescent variety of orthoclase formed at a low temperature. [1790 1800; < It < F adulaire, named after Adula a mountain group in Switzerland; see ARY] * * * ▪ mineral a feldspar mineral and… …
67syenite — syenitic /suy euh nit ik/, adj. /suy euh nuyt /, n. a granular igneous rock consisting chiefly of orthoclase and oligoclase with hornblende, biotite, or augite. [1790 1800; < L syenites (lapis) (stone) of SYENE < Gk syenítes (líthos); see ITE1] * …
68Moon rock — Olivine basalt collected by Apollo 15. Moon rock describes rock that formed on the Earth s moon. The term is also loosely applied to other lunar materials collected during the course of human exploration of the Moon. The rocks collect …
69Rock microstructure — includes the texture of a rock and the small scale rock structures. The words texture and microstructure are interchangeable, with the latter preferred in modern geological literature. However, texture is still acceptable because it is a useful… …
70Igneous rock — Geologic provinces of the world (USGS)   Shield …
