igneous

Basalt with Olivine inclusion

Mafic Volcanic Basalt (Fe,Mg)2SiO4

Hardness (Mohs): 6.0; Color: Dark grey to black matrix with brownish-green center; Luster: Dull to vitreous; Crystal Structure: Aphanitic matrix, granular phenocrysts; Cleavage: None/Conchoidal

Color: Dark grey to black matrix with brownish-green center
Luster: Dull to vitreous

Identified May 28, 2026More igneous →

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Physical properties

Hardness (Mohs): 6.0; Color: Dark grey to black matrix with brownish-green center; Luster: Dull to vitreous; Crystal Structure: Aphanitic matrix, granular phenocrysts; Cleavage: None/Conchoidal

Formation & geological history

Formed from the rapid cooling of magnesium-rich and iron-rich lava. The central mass likely represents an olivine basalt or peridotite xenolith from the mantle, brought to the surface during volcanic eruption.

Uses & applications

Primarily used in construction as crushed stone or aggregate. High-quality olivine components (peridot) are used in jewelry. Significant for geological research of the Earth's mantle.

Geological facts

Basalt is the most common rock in Earth's crust and makes up most of the ocean floor. Large olivine inclusions can sometimes contain gem-quality peridot.

Field identification & locations

Identify in the field by the heavy weight and dark, fine-grained matrix with embedded green/brown glassy crystals. Commonly found in volcanic regions such as Hawaii, Iceland, and the Pacific Northwest.

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