Orig., a rock composed of quartz, hornblende, and feldspar, anciently quarried at Syene, in Upper Egypt, and now called granite.
A granular, crystalline, ingeous rock composed of orthoclase and hornblende, the latter often replaced or accompanied by pyroxene or mica. Syenite sometimes contains nephelite (elæolite) or leucite, and is then called nephelite (elæolite) syenite or leucite syenite.
A granular, igneous rock composed of orthoclase with or without microcline, plagioclase, hornblende, biotite, and augite. May be considered a granite without quartz.
is an intrusive rock that can be regarded as silica poor granite. It consists of mainly feldspar sometimes with minor mica and quartz.
Igneous rock containing alkali feldspars. Contains mica and pyroxene minerals.
A wholly crystalline rock resembling granite but containing little or no quartz.
Whitish igneous rock composed mainly of feldspar. It is mined for its feldspar or as freestone.
Intrusive igneous rock composed of dominant alkaline feldspar.
Medium-gray, fine- to coarse-grained intrusive igneous rock, commonly massive-appearing, generally lacking layering or banding, composed primarily of potassium feldspar with minor dark minerals but little quartz.
An intrusive igneous rock consisting of mostly feldspar, with a little hornblende or biotite.
Orthoclase (Potassium) feldspar greater than 2/3 total feldspar, quartz less than 10
An intrusive rock containing alkali feldspar, with minor plagioclase and mafic minerals and little quartz; similar to granite, but less quartz-rich
Syenite 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 (<5%).