igneous
Gabbro or Diorite with Quartz/Epidote Vein
Intrusive Igneous Rock (Plutonic)
Phaneritic (coarse-grained) texture displaying mottled dark hornblende/pyroxene and light plagioclase feldspar, crosscut by a distinct lighter-colored vein (likely quartz or epidote). Hardness roughly 6-7 on Mohs scale. Dull to vitreous luster.
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Physical properties
Phaneritic (coarse-grained) texture displaying mottled dark hornblende/pyroxene and light plagioclase feldspar, crosscut by a distinct lighter-colored vein (likely quartz or epidote). Hardness roughly 6-7 on Mohs scale. Dull to vitreous luster.
Formation & geological history
Formed by the slow cooling of intermediate to mafic magma deep within the Earth's crust, producing large, visible mineral grains. The vein formed later through hydrothermal fluid injection into fractures.
Uses & applications
Crushed stone, dimension stone for construction, landscaping, and educational display.
Geological facts
The lighter band cutting across the rock is a hydrothermal vein. Hydrothermal fluids rich in dissolved minerals passed through cracks in the cooled plutonic rock, depositing new minerals like quartz or epidote over time.
Field identification & locations
Look for a salt-and-pepper or dark-speckled coarse texture combined with a continuous mineral vein cutting straight across the matrix. Commonly found in mountainous regions with exposed plutons, glacial till, and riverbeds.
