Syenites are products of alkaline igneous activity, generally formed in thick continental crustal areas, or in Cordilleran subduction zones. The formation of syenites can be theorized to be from the melt of granitic or igneous protolith to a fairly low degree of partial melting.

2023年10月20日 · Syenite is a coarse-grained, plutonic (intrusive) igneous rock that primarily consists of the minerals feldspar, typically orthoclase feldspar, and often includes smaller amounts of other minerals such as hornblende, mica, or amphibole. Unlike granite, which is another common intrusive igneous rock, syenite contains minimal to no quartz. The ...

Syenite, any of a class of intrusive igneous rocks essentially composed of an alkali feldspar and a ferromagnesian mineral. A special group of alkali syenites is characterized by the presence of a feldspathoid mineral such as nepheline, leucite, cancrinite, or sodalite (see nepheline syenite).

Syenite is an intrusive igneous rock composed primarily of alkali feldspar, lesser amounts of of plagioclase feldspar, and under 20% quartz. It is coarse-grained with tightly interlocking crystals. Syenite is usually off-white, gray, greenish, red, or pink with black spots and no …

2023年7月6日 · Syenite is a coarse-grained, mostly light-colored intrusive rock with an intermediate to felsic composition. It has mainly alkali feldspar, lesser plagioclase, and one or more mafic minerals. Also, it may have a small amount of quartz.

It is an intrusive igneous rock that consists of ferromagnesian mineral & alkali feldspar and usually coarse-grained. If we talk about its composition, that is generally the same as granite. It contains medium quantities of silica & large amounts of alkalis and alumina.

Syenite is an igneous rock that solidified slowly in the crust in a similar manner to granite. A true syenite (sensu stricto) is also compositionally resembling granite. The most notable difference is the absence or very low quantity of quartz while it is an essential component of granite.

Its name is derived from Syene, Egypt. A.G. Werner in 1788 applied the name in its present meaning; the Egyptian rock is now classified as a granite, containing much quartz. A coarse grained, felsic igneous Rock having an alkali-feldspar / plagioclase ratio from 65-90% and felsic minerals contain <5% quartz.

Syenites are a group of plutonic igneous rocks that consist almost entirely of alkali feldspar with minor amounts of Na-rich plagioclase and that represent the intrusive counterpart of trachytes.

Syenite, from Latin "Lapis Syenitis" (lapis = stone) of Syene, from Syene (an ancient city of southern Egypt), 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%).