Scoria is a highly vesicular, dark-colored volcanic rock formed from gas-rich basaltic lava. It is easily identified by its rough, bubbly appearance and low density, which often causes it to float on water initially, though it lacks the fine-grained, frothy texture of pumice.
Is this scoria?
4-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch scoria with a known reference. Scoria sits at Mohs 5-6, softer than the next harder reference, harder than the previous one.
- 2Read the textureLook at a fresh break with a hand lens. Texture: Highly vesicular, with macroscopic ellipsoidal vesicles.
- 3Read the lusterHold the specimen under a strong light. Luster: dull.
- 4Match the color rangeCompare against the expected color range: black, dark gray, reddish brown, dark red.
Often confused with
Scoria vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside scoria
Minerals reported to co-occur with scoria. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Mohs hardness
- 5-6
- Density
- 2.0-2.5 g/cm³
- Luster
- Dull
- Transparency
- Opaque
- Rarity
- Common
- Uses
- Landscaping, Road construction, Filtration media, Industrial aggregate
- Host rock
- volcanic cones and lava flows
- Texture
- Highly vesicular, with macroscopic ellipsoidal vesicles
Where rockhounds find scoria
Classic worldwide localities
- Iceland
- Italy
- Hawaii
- Mexico
- United States
Field-hunting tip
Where it forms: volcanic cones and lava flows. If you start seeing olivine, plagioclase, pyroxene in float, you are in the right ground.
Common questions
How do you identify scoria?+
Where is scoria found?+
What rocks look like scoria?+
What minerals are found with scoria?+
What kind of rock does scoria form in?+
What is scoria used for?+
Find scoria on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
