igneous

Red Scoria (Lava Rock)

Scoria (Vesicular Basalt)

Hardness: 5-6 Mohs. Color: Deep reddish-brown to dark maroon. Luster: Dull/Earthy. Structure: Highly vesicular (pitted with air bubbles), glass-like fine crystalline matrix. Specific Gravity: Variable but often low enough to be relatively lightweight.

Hardness: 5-6 Mohs
Color: Deep reddish-brown to dark maroon
Luster: Dull/Earthy

Identified March 15, 2026More igneous →

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Physical properties

Formation & geological history

Formed from the rapid cooling of basaltic or andesitic magma containing high amounts of dissolved gas. As the magma erupts, gases expand and escape, leaving behind a 'frothy' stone. Found in volcanic cinder cones globally.

Uses & applications

Commonly used in landscaping (mulch replacement), gas grills for heat retention, drainage systems, high-temperature insulation, and lightweight concrete aggregate.

Geological facts

Unlike pumice, which is similar but lighter in color and more buoyant, scoria sinks in water because its vesicle walls are thicker and the rock has a more mafic (iron-rich) chemical composition.

Field identification & locations

Identify in the field by its distinctive 'honeycomb' texture, rough surface, and reddish color caused by the oxidation of iron during eruption. It is ubiquitous in volcanic regions like the American Southwest, Iceland, and Italy.

Other igneous specimens

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Blue Apatite

Fluorapatite (Ca5(PO4)3F)

mineral

Dark Igneous Rock (Likely Basalt or Diabase)

Basalt (extrusive igneous rock) or Diabase (intrusive igneous rock - also known as Dolerite), largely composed of plagioclase feldspar, pyroxene (augite), and sometimes olivine and amphibole. Exact mineralogy would require thin section analysis.

Igneous