Pumice is a highly vesicular, low-density volcanic glass formed during explosive eruptions of silica-rich magma. It is unique for its ability to float on water due to its porous structure and is commonly found in association with rhyolitic lava flows.

Hardness

5.5-6

Mohs

Luster

Dull

Transparency

Opaque

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Pumice

Hardness: 5.5-6
Luster: Dull
Transparency: Opaque

Is this pumice?

5-step field check

Run through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.

1
Test the hardness
Try to scratch pumice with a known reference. Pumice sits at Mohs 5.5-6, softer than the next harder reference, harder than the previous one.
2
Read the texture
Look at a fresh break with a hand lens. Texture: Extremely vesicular and rough-textured. Grain size: Glassy.
3
Pick out the minerals
Composition: Highly microvesicular volcanic glass, which may contain crystals. Identify the two or three most abundant grains.
4
Read the luster
Hold the specimen under a strong light. Luster: dull.
5
Match the color range
Compare against the expected color range: white, gray, cream, light brown.

Often confused with

Pumice vs. its common look-alikes, and how to tell them apart in the field.

How to tell apart: Luster reads dull on Pumice and pearly on Perlite.

Compare →

Often found alongside pumice

Minerals reported to co-occur with pumice. Spotting these in float or country rock is a strong cue you are in the right ground.

All properties

Mohs hardness: 5.5-6
Density: 0.25-0.9 g/cm³
Colors: White Gray Cream Light brown
Luster: Dull
Transparency: Opaque
Rarity: Common
Uses: Industrial, Decorative, Lapidary
Host rock: volcanic extrusive
Texture: Extremely vesicular and rough-textured
Grain size: Glassy
Composition: Highly microvesicular volcanic glass, which may contain crystals

Where rockhounds find pumice

1 mapped spots

Classic worldwide localities

Italy
Greece
United States
New Zealand
Turkey

Field-hunting tip

Where it forms: volcanic extrusive. If you start seeing obsidian, rhyolite, trachyte in float, you are in the right ground. In the U.S., the densest reported localities are in Nevada. Start trip planning there.

Browse 1 U.S. spots for pumice →

Common questions

How do you identify pumice?+

Mohs hardness is 5.5-6. Texture: Extremely vesicular and rough-textured. Composition: Highly microvesicular volcanic glass, which may contain crystals. Luster: dull. Common colors include white, gray, cream, light brown.

Where is pumice found?+

Notable localities include Italy; Greece; United States; New Zealand; Turkey.

Can I find pumice in the United States?+

RockHoundR maps 1 pumice rockhounding spots across 1 U.S. states. The top states are Nevada.

What rocks look like pumice?+

Pumice is most often confused with Scoria, Perlite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with pumice?+

Pumice commonly co-occurs with Obsidian, Rhyolite, Trachyte. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does pumice form in?+

Where it forms: volcanic extrusive. Working float back to the host body is the standard way to chase a fresh occurrence.

What is pumice used for?+

Pumice is used in industrial, decorative, lapidary.

Find pumice on the map

RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.