igneous

Dalmatian Stone

Dalmatian Jasper (Aphanitic Igneous Rock with Arfvedsonite inclusions)

Hardness: 5.5 to 7 on the Mohs scale; Color: Creamy white or gray background with black or dark brown spots; Luster: Vitreous to dull; Crystal structure: Microcrystalline; Cleavage: None; Specific Gravity: 2.58 - 2.91

Hardness: 5
Luster: Vitreous to dull

Identified March 16, 2026More igneous →

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Physical properties

Formation & geological history

Formed from peralkaline volcanic activity, specifically as a variety of felsic igneous rock where silica-rich magma cools quickly. Most commercial specimens are sourced from Chihuahua, Mexico. Its age is generally associated with Tertiary volcanic formations.

Uses & applications

Primarily used for decorative purposes including jewelry (beads, cabochons), carvings, tumble finishing for collectors, and metaphysical practices (often called a 'grounding' stone).

Geological facts

Despite being commonly marketed as 'Dalmatian Jasper,' it is geologically an igneous rock, not a true sedimentary Jasper. The black spots were long thought to be Tourmaline but are actually Arfvedsonite (an amphibole mineral).

Field identification & locations

Identify in the field by its distinct 'dalmatian dog' spotted pattern and its lack of reaction to acid. It is found exclusively in Mexico. Collectors should look for a smooth, matte to waxy texture and well-defined black spots.

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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.

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Iron(II,III) oxide (Fe3O4)

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Magnetite

Magnetite (Fe3O4)

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