Red Scoria

Mohs hardness 5-6, reddish-brown to dark red, dull to earthy luster, highly vesicular (full of small cavities/holes) texture, rough feel, low density relative to solid basalt

Formed during explosive volcanic eruptions when gas-rich basaltic or andesitic lava is ejected into the air and cools rapidly, trapping expanding gas bubbles. The red color comes from oxidation of iron during or after cooling.

Widely used in landscaping (lava rock), drainage systems, high-temperature insulation, gas grills, lightweight concrete aggregate, and decorative gardening.

Scoria floats on water briefly until its pores fill with water, unlike pumice which can float indefinitely. Its red color is a result of iron minerals oxidizing in the presence of heat and oxygen.

Identified in the field by its distinct reddish-brown color, lightweight feel, and sponge-like vesicular texture with jagged, micro-porous surface. Commonly found in volcanic fields, basaltic cinder cones, and sold at garden supply stores.