igneous

Granite with Orthoclase and Hematite Staining

Phaneritic Felsic Igneous Rock (primarily SiO2 with KAlSi3O8)

Hardness: 6-7 on Mohs scale; Color: Mottled tan, grey, and pink/rust; Luster: Dull to vitreous; Crystal structure: Phaneritic (coarse-grained); Cleavage: Good in two directions for feldspar components; Specific gravity: 2.6-2.7 g/cm³

Hardness: 6-7 on Mohs scale
Color: Mottled tan, grey, and pink/rust
Luster: Dull to vitreous

Identified March 29, 2026More igneous →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Formed through the slow crystallization of magma below Earth's surface. The pinkish-red staining is likely caused by secondary iron oxide (hematite) or a high concentration of potassium-rich orthoclase feldspar. Age can range from Precambrian to Cenozoic depending on the specific pluton.

Uses & applications

Used extensively in construction as aggregate, countertops, and decorative masonry. Smaller rough specimens like this are primarily used for geological study or classroom examples.

Geological facts

Granite makes up the majority of the Earth's continental crust. The distinct red/purple patch on this specimen suggests localized oxidation or hydrothermal alteration after the initial rock solidified.

Field identification & locations

Identify in the field by looking for visible interlocking crystals of quartz and feldspar; look for its high resistance to weathering. Found globally in mountainous regions. Collectors should look for unique mineral inclusions or large phenocrysts.

Other igneous specimens

See all

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