igneous
Basalt with Epidote (Porphyritic Basalt)
Mafic Porphyritic Basalt with (Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)) inclusions
Hardness: 6-7 Mohs; Color: Dark grey to black matrix with greenish-yellow (epidote) crystals; Luster: Dull to waxy; Texture: Porphyritic or amygdaloidal.
- Hardness
- 6-7 Mohs
- Luster
- Dull to waxy
Identified More igneous →
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Physical properties
Hardness: 6-7 Mohs; Color: Dark grey to black matrix with greenish-yellow (epidote) crystals; Luster: Dull to waxy; Texture: Porphyritic or amygdaloidal.
Formation & geological history
Formed from the rapid cooling of magnesium-rich and iron-rich lava at or near the Earth's surface. The green patches are likely epidote, a secondary mineral formed during low-grade metamorphism or hydrothermal alteration of the basalt.
Uses & applications
Commonly used as crushed stone in construction, road base, and as a decorative landscaping stone or aquarium rock.
Geological facts
Basalt is the most common rock type on Earth's crust and makes up most of the ocean floor. The green mineral epidote is often used as a marker for certain types of hydrothermal activity.
Field identification & locations
Identified by its heavy weight (high density), dark matrix, and characteristic 'pistachio green' inclusions of epidote. Often found in volcanic regions or glacial till.
