igneous

Pink Granite (River Pebble)

Phaneritic Felsic Igneous Rock

Hardness: 6-7 (Mohs); Color: Pink to orange-red with black and grey specks; Luster: Dull (weathered) to vitreous (fresh break); Crystal Structure: Phaneritic (visible crystals of quartz, K-feldspar, and mica); Cleavage: None for the rock as a whole

Hardness: 6-7 (Mohs)
Color: Pink to orange-red with black and grey specks
Luster: Dull (weathered) to vitreous (fresh break)

Identified March 21, 2026More igneous →

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Physical properties

Formation & geological history

Formed from the slow cooling of silica-rich magma deep underground (plutonic). This specific specimen has been rounded by fluvial processes (water erosion in a river or glacial stream) over thousands to millions of years.

Uses & applications

Used widely in construction as crushed stone, dimension stone for countertops and monuments, and as decorative landscaping gravel.

Geological facts

The pink color comes specifically from Potassium Feldspar (Orthoclase). Granite makes up the majority of the Earth's continental crust and is incredibly resistant to weathering, which is why it often survives as rounded pebbles in riverbeds.

Field identification & locations

Identify in the field by its 'salt and pepper' appearance with a pinkish hue and hardness; it will easily scratch glass. Commonly found in mountainous regions, glacial till, or riverbeds downstream from igneous outcrops.

Other igneous specimens

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Blue Apatite

Fluorapatite (Ca5(PO4)3F)

mineral

Dark Igneous Rock (Likely Basalt or Diabase)

Basalt (extrusive igneous rock) or Diabase (intrusive igneous rock - also known as Dolerite), largely composed of plagioclase feldspar, pyroxene (augite), and sometimes olivine and amphibole. Exact mineralogy would require thin section analysis.

Igneous

Magnetite

Iron(II,III) oxide (Fe3O4)

mineral

Sodalite

Sodalite - Na8(Al6Si6O24)Cl2

mineral

Blue Apatite

Apatite (Group), Ca5(PO4)3(F,Cl,OH)

mineral

Magnetite

Magnetite (Fe3O4)

mineral