igneous
Granite Pebble (Pegmatitic Quartz-Feldspar River Rock)
Granite / Quartz-Feldspar-Mica Aggregate
Hardness 6-7 on Mohs scale. Color ranges from milky white to peach/pinkish tan with grey and dark mica or tourmaline/amphibole inclusions. Luster is vitreous to dull due to water weathering. Texture is coarse-grained, showing interlocking mineral grains of quartz, feldspar, and mica.
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Physical properties
Hardness 6-7 on Mohs scale. Color ranges from milky white to peach/pinkish tan with grey and dark mica or tourmaline/amphibole inclusions. Luster is vitreous to dull due to water weathering. Texture is coarse-grained, showing interlocking mineral grains of quartz, feldspar, and mica.
Formation & geological history
Formed deep underground through the slow cooling and crystallization of felsic magma. Over geological time, erosion and transport by rivers or streams rounded the rock into a smooth river cobble.
Uses & applications
Commonly used in landscaping, river rock decor, aggregate for construction, and as a educational or hand-held rock specimen.
Geological facts
Granite is one of the most common rocks in the Earth's continental crust. The pink or peach tones come from potassium feldspar (orthoclase), while the translucent/milky areas consist of quartz.
Field identification & locations
Identified by its water-worn rounded shape, mixed granular texture, and visible interlocking mineral crystals of quartz and feldspar. Found abundantly in riverbeds, glacial deposits, and gravel pits worldwide.
