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.

Hardness

5-6

Mohs

Luster

Dull

Streak

White

Transparency

Opaque

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Scoria

Hardness: 5-6
Luster: Dull
Streak: White
Transparency: Opaque

Is this scoria?

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 scoria with a known reference. Scoria sits at Mohs 5-6 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Scoria leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Scoria typically shows a dull luster.
4
Match the color range
Compare against the expected color range: black, dark gray, reddish brown, dark red.
5
Look at form & habit
Typical habit: vesicular.

Often confused with

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

How to tell apart: Streak differs — Scoria leaves white, Vesicular Basalt leaves white to gray.

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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
Colors: Black Dark Gray Reddish Brown Dark Red
Streak: White
Luster: Dull
Transparency: Opaque
Crystal habit: Vesicular
Cleavage: None
Rarity: Common
Uses: Landscaping, Road Construction, Filtration Media, Industrial Aggregate
Host rock: Volcanic Cones and Lava Flows
Typical price: $1-5 per pound as landscaping aggregate

Where rockhounds find scoria

Classic worldwide localities

Iceland
Italy
Hawaii
Mexico
United States

Field-hunting tip

Look in volcanic cones and lava flows country — that is the host setting where scoria typically forms. If you start seeing olivine, plagioclase, pyroxene in float, you are in the right ground. Field specimens usually show a vesicular habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify scoria?+

Mohs hardness is 5-6. It typically shows a dull luster. The streak is white. Common colors include black, dark gray, reddish brown, dark red.

Where is scoria found?+

Notable localities include Iceland; Italy; Hawaii; Mexico; United States.

How much is scoria worth?+

Typical asking prices fall in the range of $1-5 per pound as landscaping aggregate. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like scoria?+

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

What minerals are found with scoria?+

Scoria commonly co-occurs with olivine, plagioclase, pyroxene. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does scoria form in?+

Scoria typically forms in volcanic cones and lava flows. Working float back to the host body is the standard way to chase a fresh occurrence.

What is scoria used for?+

Scoria is used in landscaping, road construction, filtration media, industrial aggregate.

Find scoria on the map

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