dolerite
noun
dol·er·ite ˈdä-lə-ˌrīt 
1
: any of various coarse basalts
2
chiefly British : diabase sense 3
doleritic
ˌdä-lə-ˈri-tik
adjective 
Example Sentences
Recent Examples on the Web One quarry, an outcrop called Carn Goedog, seems to have supplied most of the bluish-gray, white-speckled dolerite at Stonehenge. 
Jennifer Ouellette, Ars Technica, 8 Mar. 2022 The singular characteristic of these bays was Great Whin Sill, a band of igneous dolerite — a dusky, crystalline rock — that erupted from the sea in stratified cliffs and headlands. Henry Wismayer, Washington Post, 8 Sep. 2021
Jennifer Ouellette, Ars Technica, 8 Mar. 2022 The singular characteristic of these bays was Great Whin Sill, a band of igneous dolerite — a dusky, crystalline rock — that erupted from the sea in stratified cliffs and headlands. Henry Wismayer, Washington Post, 8 Sep. 2021 Word History
Etymology
French dolérite, from Greek doleros deceitful, from dolos deceit; from its being easily mistaken for diorite
First Known Use
1838, in the meaning defined at sense 1