syenite
/ˈsʌɪənʌɪt
/noun [mass noun] Geology
A coarse-grained grey igneous rock composed mainly of alkali feldspar and ferromagnesian minerals such as hornblende.The southern Zomba area consists mainly of syenite surrounded by a periphery of alkaline granite....
- A violet, coarse-grained, porphyritic quartz syenite, which makes up large parts of the pluton, was collected for dating.
- The selective removal of these minerals resulted in a change of the composition of the magma to one near that of the rock syenite.
Derivatives
syenitic
- Of far less importance are occurrences in gneisses and amphibolites, in small plutons derived from syenitic and gabbroic magmas, and in certain contact-metamorphic rocks.
- In the central part of the intrusion, some small granitic aplite dykes intrude the syenitic rocks.
- Several pools of syenitic magma were separated from the main body of the melt.
Origin
Late 18th century: from French syénite, from Latin Syenites (lapis) '(stone) of Syene' (from Greek Suēnē Aswan in Egypt).