Scoria

About it

Dark, bubbly lava rock that is heavier than pumice and usually sinks, often black or oxidized red. Builds cinder cones such as Sunset Crater, Arizona, and is sold as lava rock for landscaping.

Type

Rock (igneous)

Group

Igneous (volcanic)

Lustre

dull

Colours

black, dark grey, red, red-brown

Transparency

opaque

Typical values: real specimens vary. For more, see mindat.org.