igneous

Pumice

Pumice (a highly vesicular extrusive igneous rock)

Hardness: 5-6 (but very brittle); Color: light gray, white, or cream; Luster: dull to pearly; Structure: highly vesicular (full of gas bubbles); Specific Gravity: 0.6-0.9 (floats in water).

Hardness: 5-6 (but very brittle)
Color: light gray, white, or cream
Luster: dull to pearly

Identified April 4, 2026More igneous →

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Physical properties

Hardness: 5-6 (but very brittle); Color: light gray, white, or cream; Luster: dull to pearly; Structure: highly vesicular (full of gas bubbles); Specific Gravity: 0.6-0.9 (floats in water).

Formation & geological history

Formed during explosive volcanic eruptions when highly pressurized, gas-rich magma is ejected. The rapid cooling and depressurization trap gas bubbles inside as the lava solidifies into glass.

Uses & applications

Used as an abrasive in cleaning products, skin exfoliants (pumice stones), lightweight concrete, dental polishing compounds, and in stone-washed denim production.

Geological facts

Pumice is the only rock that consistently floats on water. Massive 'pumice rafts' created by underwater volcanoes can drift for thousands of miles across oceans.

Field identification & locations

Identify by its extremely light weight, frothy texture, and ability to float. It is commonly found in volcanic arc regions near the Ring of Fire or Mediterranean.

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Blue Apatite

Fluorapatite (Ca5(PO4)3F)

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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)

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Sodalite

Sodalite - Na8(Al6Si6O24)Cl2

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Blue Apatite

Apatite (Group), Ca5(PO4)3(F,Cl,OH)

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Magnetite

Magnetite (Fe3O4)

mineral