Most Common Lava Rock, Makes Up the Ocean Floor

This page is the CodyCross answer for the clue below from Mesopotamia, Group 980, Puzzle 5 (Babylonian Empire).

Question is: Most Common Lava Rock, Makes Up the Ocean Floor

and the answer is: BASALT

Word Meaning:

BASALT — (mineralogy) A hard mafic igneous rock of varied mineral content; volcanic in origin, which makes up much of the Earth's oceanic crust.

Definitions from Wiktionary.