igneous

Granite Pebble

Granite (Felsic Intrusive Igneous Rock)

Hardness: 6-7 on Mohs scale. Color: Tan, cream, and gray with dark speckles. Luster: Dull to vitreous. Crystal Structure: Phaneritic (visible grains) consisting of quartz, feldspar, and mica. Specific Gravity: 2.63 to 2.75.

Hardness: 6-7 on Mohs scale
Color: Tan, cream, and gray with dark speckles
Luster: Dull to vitreous

Identified May 30, 2026More igneous →

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Physical properties

Formation & geological history

Formed from the slow cooling of silica-rich magma deep underground. This specific specimen has been rounded and smoothed by water erosion in a river, beach, or glacial environment. Geological age can range from billions of years to more recent eras depending on the source pluton.

Uses & applications

In pebble form, used for landscaping, decorative garden paths, and aquarium gravel. In bulk stone form, used for countertops, construction, and monuments.

Geological facts

Granite makes up the majority of the Earth's continental crust. Because of its high quartz content, granite pebbles are extremely durable and can withstand chemical weathering better than many other rock types.

Field identification & locations

Identify by its 'salt and pepper' appearance and visible interlocking crystals. Can be found globally in riverbeds, glacial moraines, and along coastlines near crystalline basement rock. Collectors often look for colorful variations or unique rounding.

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Blue Apatite

Fluorapatite (Ca5(PO4)3F)

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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

Dalmatian Jasper

Aplite with Arfvedsonite inclusions

igneous

Magnetite

Iron(II,III) oxide (Fe3O4)

mineral

Blue Apatite

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

mineral

Sodalite

Sodalite - Na8(Al6Si6O24)Cl2

mineral