Pumice

About it

Frothy volcanic glass so full of gas bubbles that most pieces float on water; pale, rough to the touch, and used as an abrasive. Rafts of it can drift across oceans after big eruptions.

Type

Rock (igneous)

Group

Igneous (volcanic glass)

Lustre

vitreous (glassy), dull

Colours

white, cream, light grey, tan

Transparency

opaque

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