igneous

Red Scoria (Lava Rock)

Vesicular Basalt / Scoria

Hardness: 5-6 (Mohs scale); Color: Deep reddish-brown to dark gray; Luster: Dull to earthy; Structure: Vesicular (full of small holes or bubbles); Cleavage: None; Specific Gravity: Relatively low/light due to air pockets.

Hardness: 5-6 (Mohs scale)
Color: Deep reddish-brown to dark gray
Luster: Dull to earthy

Identified March 29, 2026More igneous →

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Physical properties

Formation & geological history

Formed from gas-rich basaltic magma that ejected from a volcano during an explosive eruption. The holes (vesicles) are created by trapped gas bubbles that freeze in place as the lava cools rapidly. Typically found in Cenozoic volcanic fields.

Uses & applications

Commonly used in landscaping (decorative rock), ground cover for fire pits, high-temperature insulation, and as a lightweight aggregate in concrete or drainage systems.

Geological facts

Scoria is different from pumice because it has thicker cell walls and is denser; unlike pumice, most scoria will sink in water. The red color is caused by the oxidation of iron within the lava while it is still hot.

Field identification & locations

Identify by its 'sponge-like' appearance, rough/sharp texture, and reddish hue. Common in regions with past volcanic activity like Arizona, Iceland, Italy, and Hawaii. Collectors look for pieces with distinct, uniform vesicles or embedded crystals.

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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