dolerite
Concise Oxford English Dictionary © 2008 Oxford University Press:
dolerite /ˈdɒlərʌɪt/
▶noun Geology a dark, medium-grained igneous rock typically occurring in dykes and sills.
– origin C19: from Fr. dolérite, from Gk doleros ‘deceptive’ (because it resembles diorite).
'dolerite' also found in these Oxford entries:

