igneous
Basalt with Peridotite Xenolith
Mafic Igneous Rock with Peridotite Inclusion (Olivine-rich)
Hardness: 6-7 (olivine) / 6 (basalt). Color: Dark gray to black matrix with a yellowish-green inclusion. Luster: Dull matrix, vitreous crystal inclusion. Structure: Aphanitic (fine-grained) matrix with granular crystalline inclusion.
- Hardness
- 6-7 (olivine) / 6 (basalt)
- Color
- Dark gray to black matrix with a yellowish-green inclusion
- Luster
- Dull matrix, vitreous crystal inclusion
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Physical properties
Hardness: 6-7 (olivine) / 6 (basalt). Color: Dark gray to black matrix with a yellowish-green inclusion. Luster: Dull matrix, vitreous crystal inclusion. Structure: Aphanitic (fine-grained) matrix with granular crystalline inclusion.
Formation & geological history
Formed when mafic magma (basaltic) rises from the mantle, breaking off and carrying pieces of solid mantle rock (peridotite) to the surface. These specimens can range from thousands to millions of years old.
Uses & applications
Scientific study of the Earth's mantle; decorative specimens for collectors; crushed basalt is used in construction and road base.
Geological facts
Xenoliths (meaning 'foreign rock') provide geologists with direct samples of the Earth's interior that are otherwise inaccessible. The green mineral is likely Olivine, which is known as Peridot when of gemstone quality.
Field identification & locations
Identify by a dark, heavy, fine-grained rock containing distinct green or yellow glassy granular clusters. Commonly found in volcanic fields such as those in Arizona, Hawaii, or the Canary Islands.
