igneous

Scoria (Basaltic Lava Rock)

Vesicular Basalt

Hardness: 5-6 (Mohs scale); Color: Black, dark gray, or reddish-brown; Luster: Dull to sub-metallic; Crystal Structure: Aphanitic (fine-grained) with a vesicular texture; Cleavage: None; Specific Gravity: Relatively low due to gas bubbles (vesicles).

Hardness: 5-6 (Mohs scale)
Color: Black, dark gray, or reddish-brown
Luster: Dull to sub-metallic

Identified April 2, 2026More igneous →

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Physical properties

Formation & geological history

Formed from extrusive volcanic activity where gas is trapped in cooling magma, creating many small holes. It is common in areas of recent volcanic activity (Quaternary period to present) such as cinder cones.

Uses & applications

Used in landscaping (lava rocks), BBQ grills, high-temperature insulation, lightweight concrete aggregate, and as a drainage material.

Geological facts

Scoria is often mistaken for pumice; however, scoria sinks in water because it has thicker cell walls and a more mafic composition, whereas pumice is more silicic and can float.

Field identification & locations

Identify by its dark color, high porosity with visible holes (vesicles), and rough, abrasive texture. Commonly found near volcanoes and mid-ocean ridges.

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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