Quadrupeds
When discussing rock art, these are animal figures with four legs.

Quarry
An open or surface working, usually for the extraction of building stone or other industrial minerals.

Quartz
An important rock-forming mineral (silicon dioxide). Quarts is second only to feldspar as the most common rock-forming mineral, and it forms the major portion of most sands. It has a widespread distribution in igneous, metamorphic, and sedimentary rocks. Quartz has a glassy luster and fracture, and lacks cleavage.

Quicksand
A mass of deep, soft, wet sand that yields easily to pressure and will not support a heavy object, but will slowly engulf it.