igneous

Diorite

Diorite (Intermediate intrusive igneous rock)

Hardness: 6-7 on Mohs scale. Color: Spotted 'salt and pepper' appearance (black and white/grey). Luster: Phaneritic (visible crystals), dull to vitreous. Crystal structure: Coarse-grained. Cleavage: Good in two directions (due to feldspar). Specific gravity: 2.8-3.0.

Hardness: 6-7 on Mohs scale
Color: Spotted 'salt and pepper' appearance (black and white/grey)
Luster: Phaneritic (visible crystals), dull to vitreous

Identified April 7, 2026More igneous →

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Physical properties

Formation & geological history

Formed by the slow cooling of magma deep beneath the Earth's surface (intrusive). Usually associated with convergent plate boundaries and volcanic arcs. Can be found in many Precambrian and Paleozoic mountain ranges.

Uses & applications

Used primarily in construction for crushed stone, base material for roads, and as a dimension stone for building facades, floor tiles, and grave markers. Occasionally used for sculptures.

Geological facts

Diorite is so hard that ancient civilizations, like the Egyptians, used it as tools to work on softer stones like granite. The Code of Hammurabi was inscribed on a large pillar of diorite.

Field identification & locations

Identify in the field by its speckled 'salt and pepper' look, lack of visible quartz (unlike granite), and coarse grain. Found in batholiths and mountainous regions worldwide (e.g., Andes, Alps). Collectors look for uniform texture and lack of weathering.

Other igneous specimens

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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

Magnetite

Iron(II,III) oxide (Fe3O4)

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Sodalite

Sodalite - Na8(Al6Si6O24)Cl2

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Blue Apatite

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

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Magnetite

Magnetite (Fe3O4)

mineral