syenite
noun
sy·e·nite ˈsī-ə-ˌnīt 
: an igneous rock composed chiefly of feldspar
syenitic
ˌsī-ə-ˈni-tik
adjective 
Example Sentences
Recent Examples on the Web Erik Rintamaki is credited with finding the sodalite-rich syenite rocks in 2017 on a Lake Superior beach near Brimley. 
USA TODAY, 15 July 2019
USA TODAY, 15 July 2019 Word History
Etymology
Latin Syenites (lapis) stone of Syene, from Syene, ancient city in Egypt
First Known Use
circa 1796, in the meaning defined above