igneous
Granite Pebble
Granite
Hardness: 6-7 on Mohs scale. Color: Off-white to light gray with dark speckles (biotite/amphibole). Luster: Dull to vitreous. Texture: Phaneritic (medium-grained intrusive), rounded by erosion.
- Hardness
- 6-7 on Mohs scale
- Luster
- Dull to vitreous
Identified More igneous →
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Physical properties
Hardness: 6-7 on Mohs scale. Color: Off-white to light gray with dark speckles (biotite/amphibole). Luster: Dull to vitreous. Texture: Phaneritic (medium-grained intrusive), rounded by erosion.
Formation & geological history
Formed by the slow crystallization of silica-rich magma deep beneath the Earth's surface. This specific specimen has been rounded by water or glacial erosion in stream beds, beaches, or glacial till.
Uses & applications
Granite is widely used as a construction material, countertop surface, dimension stone, and aggregate. Small tumbled or river pebbles are used in landscaping, aquariums, and casual rock collections.
Geological facts
Granite makes up a large portion of Earth's continental crust. The dark speckles are typically biotite mica or hornblende, while the light background is composed of quartz and feldspar minerals.
Field identification & locations
Identified by its visible interlocking mineral grains of quartz (glassy light gray) and feldspar (milky white/pink) speckled with dark minerals. Common in riverbeds, lake shores, and mountain streams globally.
