tholeiite

noun

tho·​lei·​ite ˈtō-lə-ˌīt  ˈthō- 

: a basaltic rock that is rich in aluminum and low in potassium, is found typically in the ocean floor, and is probably derived from the earth's mantle

tholeiitic

ˌtō-lə-ˈi-tik 

ˌthō-

adjective

Word History

Etymology

German Tholeiit, from Tholey, village in Saarland, Germany + German -it -ite

First Known Use

1866, in the meaning defined above