igneous

Granite

Granite (Felsic Plutonic Rock)

Hardness: 6-7 on Mohs scale; Color: Pinkish-red (orthoclase), gray, and black (biotite/amphibole); Luster: Dull to vitreous; Crystal structure: Phaneritic (coarse-grained); Specific gravity: 2.63-2.75

Hardness: 6-7 on Mohs scale
Luster: Dull to vitreous

Identified May 4, 2026More igneous →

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Physical properties

Formation & geological history

Formed from the slow crystallization of magma below the Earth's surface. This specimen appears to be a weathered fragment of pink granite, likely millions to billions of years old from an intrusive igneous body.

Uses & applications

Widely used in construction, countertops, monuments, curbing, and as crushed stone for road base. Minor use in high-end garden lapidary.

Geological facts

Granite makes up a large part of the Earth's continental crust. Mount Rushmore is carved into a massive granite batholith in South Dakota.

Field identification & locations

Identify by its interlocking crystalline texture containing pink feldspar, clear-gray quartz, and dark specks of mica or hornblende. Can be found in mountainous regions or glacial till worldwide.

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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