igneous

Crushed Granite Gravel

Granite (Mainly Quartz, Feldspar, and Mica)

Hardness: 6-7 on Mohs scale; Color: typically mottled grey, white, and pink with dark specks; Luster: Dull to vitreous; Crystal structure: Phaneritic (coarse-grained); Cleavage: Indistinct; Specific gravity: 2.63 to 2.75.

Hardness: 6-7 on Mohs scale
Color: typically mottled grey, white, and pink with dark specks
Luster: Dull to vitreous

Identified March 17, 2026More igneous →

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Physical properties

Formation & geological history

Formed through the slow crystallization of magma below Earth's surface (intrusive). Geological age varies by source but ranges from the Precambrian to the Cenozoic. These specimens specifically are mechanically crushed for landscaping use.

Uses & applications

Primarily used as construction aggregate, road base, landscaping mulch, and driveways. High-quality slabs are used for countertops and monuments.

Geological facts

Granite makes up a large part of the Earth's continental crust. It is one of the hardest and most durable common stones, making it a favorite for architectural endurance.

Field identification & locations

Identify in the field by its 'salt and pepper' appearance and visible interlocking crystals. It is commonly found in mountain ranges and gravel pits worldwide. For collectors, look for versions with high pink potassium feldspar or large mica flakes.

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