igneous
Pumice
Pumiceous rhyolite
Hardness: 5-6 Mohs. Color: light gray to whitish. Luster: vitreous to dull. Crystal structure: amorphous/vesicular. Specific gravity: <1.0 (floats on water).
- Hardness
- 5-6 Mohs
- Color
- light gray to whitish
- Luster
- vitreous to dull
Identified More igneous →
Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 5-6 Mohs. Color: light gray to whitish. Luster: vitreous to dull. Crystal structure: amorphous/vesicular. Specific gravity: <1.0 (floats on water).
Formation & geological history
Extrusive volcanic rock formed when highly pressurized lava is violently ejected from a volcano, cooling rapidly while gas bubbles are trapped inside.
Uses & applications
Used as an abrasive in polishing, skin exfoliation (pumice stones), lightweight aggregate in concrete, and in horticulture for soil aeration.
Geological facts
Pumice is the only rock that can float on water due to its high porosity. Large 'pumice rafts' can form in the ocean after major submarine eruptions.
Field identification & locations
Identify by its incredibly light weight, frothy 'sponge-like' appearance, and ability to float. Commonly found near active or dormant volcanic regions.
More like this
Other igneous specimens
Blue Apatite
Fluorapatite (Ca5(PO4)3F)
mineral
Dark Igneous Rock (Likely Basalt or Diabase)
Basalt (extrusive igneous rock) or Diabase (intrusive igneous rock - also known as Dolerite), largely composed of plagioclase feldspar, pyroxene (augite), and sometimes olivine and amphibole. Exact mineralogy would require thin section analysis.
Igneous
Magnetite
Iron(II,III) oxide (Fe3O4)
mineral
Sodalite
Sodalite - Na8(Al6Si6O24)Cl2
mineral
Blue Apatite
Apatite (Group), Ca5(PO4)3(F,Cl,OH)
mineral
Magnetite
Magnetite (Fe3O4)
mineral