Definitions

1. adjective

Of or relating to a type of volcanic rock, typically dark-colored and containing a high proportion of iron and magnesium.

“The geologist studied the tholeiitic lava flows that formed the mountain range.”

2. noun

A type of volcanic rock or lava, typically dark-colored and containing a high proportion of iron and magnesium.

“The tholeiitic rocks in the region were found to be rich in iron ore.”