What's That Rock?Scoria
A dark red, brown or black volcanic rock full of gas bubbles. Heavier than pumice, it sinks in water.
How to identify Scoria
- Full of round holes
- Sinks in water, unlike pumice
- Rough, lightweight and dark
Often confused with
- Pumicefloats
- Slagman-made
- Basalt with a few holes
Real or fake?
- Slag from furnaces looks similar; scoria is natural and has a vesicle pattern, slag often has glassy layers
Is Scoria valuable?
Inexpensive.
What changes the price
- Common rock: very low value
- Landscaping scoria is sold by the bag or ton
- Grill and aquarium use is also cheap
Uses
- Landscaping, barbecue stones, lightweight concrete
Care
Brittle and sharp when broken.
Identifying a stone from a description or a photo is an estimate. Many stones look alike. Ask an expert or a gem lab before you buy, sell or rely on an identification.
Updated October 2026