igneous

Granite Pebble (Weathered)

Phaneritic Felsic Igneous Rock

Hardness: 6-7 (Mohs scale); Color: Grayish-white with dark speckles; Luster: Dull to vitreous; Crystal structure: Phaneritic (visible interlocking grains); Cleavage: Uneven fracture; Specific gravity: 2.63 - 2.75

Hardness: 6-7 (Mohs scale)
Color: Grayish-white with dark speckles
Luster: Dull to vitreous

Identified March 25, 2026More igneous →

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Physical properties

Formation & geological history

Formed through the slow crystallization of magma below Earth's surface. This specimen appears as a small, rounded pebble likely weathered and eroded from a larger plutonic body and transported by water or glacier.

Uses & applications

Used widely in construction (aggregate, dimension stone), kitchen countertops, and as road ballast. Small weathered fragments like this are often part of gravel used for landscaping or paving.

Geological facts

Granite makes up a large portion of the Earth's continental crust. Most granite occurs in the core of mountain ranges. It is resistant to acid rain and decay, making it a favorite for outdoor monuments.

Field identification & locations

Identify by looking for 'salt and pepper' appearance caused by quartz, feldspar, and mica minerals. Found globally in continental shields. Collectors look for larger, unweathered specimens with sharp crystal faces or rare mineral inclusions.

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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)

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Sodalite

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Blue Apatite

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

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Magnetite

Magnetite (Fe3O4)

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