Scoria vs. Pumice — What's the Difference?

Scoria is a highly vesicular, dark-colored volcanic rock that may or may not contain crystals (phenocrysts). It is typically dark in color (generally dark brown, black or purplish red), and basaltic or andesitic in composition.

Pumice ( ), called pumicite in its powdered or dust form, is a volcanic rock that consists of highly vesicular rough textured volcanic glass, which may or may not contain crystals. It is typically light colored.

(Geology) Porous cinderlike fragments of dark lava. Also called cinders, slag.

A light, porous, glassy lava, used in solid form as an abrasive and in powdered form as a polish and an abrasive.

(Metallurgy) The refuse of a smelted metal or ore; slag. Also called cinder.

To clean, polish, or smooth with pumice.

The slag or dross that remains after the smelting of metal from an ore.

A light, porous type of pyroclastic igneous rock, formed during explosive volcanic eruptions when liquid lava is ejected into water or air as a froth containing masses of gas bubbles, which are frozen into the rock as the lava solidifies.

(geology) Rough masses of rock formed by solidified lava, and which can be found around a volcano's crater.

(transitive) To abrade or roughen with pumice.

The recrement of metals in fusion, or the slag rejected after the reduction of metallic ores; dross.

A very light porous volcanic scoria, usually of a gray color, the pores of which are capillary and parallel, giving it a fibrous structure. It is supposed to be produced by the disengagement of watery vapor without liquid or plastic lava. It is much used, esp. in the form of powder, for smoothing and polishing. Called also pumice stone.

Cellular slaggy lava; volcanic cinders.

A light glass formed on the surface of some lavas; used as an abrasive

The scum formed by oxidation at the surface of molten metals