diabase
noun
di·a·base ˈdī-ə-ˌbās 
1
archaic : diorite
2
chiefly British : an altered basalt
3
: a fine-grained rock of the composition of gabbro but with an ophitic texture
diabasic
ˌdī-ə-ˈbā-sik
adjective 
Example Sentences
Recent Examples on the Web It’s made of diabase traprock, which contains iron that causes the cliffs to look lumpen and rusty in the wrong light, precise and resplendent in the right one. 
Christian Wiman, Harper's magazine, 20 Jan. 2020
Christian Wiman, Harper's magazine, 20 Jan. 2020 Word History
Etymology
French, probably from Greek diabasis act of crossing over, from diabainein to cross over, from dia- + bainein to go — more at come
First Known Use
1811, in the meaning defined at sense 1