igneous
Diabase / Dolerite with Weathered Matrix
Diabase (or microgabbro)
Hardness: 6-7 on Mohs scale; Color: Dark gray to black with speckled lighter plagioclase laths; Luster: Sub-metallic to dull; Crystal structure: Diabasic or ophitic texture with interlocking plagioclase and pyroxene crystals; Specific gravity: 2.8-3.0.
- Hardness
- 6-7 on Mohs scale
- Color
- Dark gray to black with speckled lighter plagioclase laths
- Luster
- Sub-metallic to dull
Identified More igneous →
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Physical properties
Hardness: 6-7 on Mohs scale; Color: Dark gray to black with speckled lighter plagioclase laths; Luster: Sub-metallic to dull; Crystal structure: Diabasic or ophitic texture with interlocking plagioclase and pyroxene crystals; Specific gravity: 2.8-3.0.
Formation & geological history
Formed as an intrusive igneous rock, crystallizing from mafic magma in shallow dikes, sills, or subvolcanic intrusions. Geological age varies widely depending on the specific intrusion site.
Uses & applications
Used extensively in construction, as crushed stone for roadbeds, railroad ballast, and building dimension stone.
Geological facts
Diabase occupies an intermediate position between fine-grained basalt and coarse-grained gabbro. Its interlocking crystal texture gives it exceptional toughness and resistance to crushing.
Field identification & locations
Identified by its distinctive salt-and-pepper dark appearance with visible interlocking plagioclase laths, often found in glacial erratic pebbles or eroded dike structures. Common worldwide.
