Definitions:

1. A coarse-grained, dark-colored, intrusive igneous rock, that forms from the slow cooling of magma deep beneath the Earth's surface, often used in construction and as a crushed stone for road building due to its durability. NOUN
   • Geologists found large deposits of gabbro, indicating the area had experienced significant volcanic activity.
   • The road construction used crushed gabbro for the base layer because of its strength and durability.

Synonyms:

• basalt
• diorite
• intrusive igneous rock