igneous

Dalmatian Jasper

Dalmatian Stone (a microcrystalline quartz and feldspar rock with arfvedsonite)

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

Hardness: 5
Luster: Vitreous to dull

Identified March 3, 2026More igneous →

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Physical properties

Formation & geological history

Formed primarily from volcanic activity in Mexico, it is a peralkaline rock consisting of a mixture of feldspar and quartz (the matrix) with black spots composed of the amphibole mineral arfvedsonite.

Uses & applications

Commonly used in lapidary work for beads, cabochons, carvings, and ornamental objects. It is also popular in holistic practices and as a collector's stone due to its unique pattern.

Geological facts

Despite being marketed as 'Jasper,' it is technically an igneous rock rather than a sedimentary chalcedony. The name comes from its resemblance to the Dalmatian dog breed.

Field identification & locations

Identified by its distinctive 'spotted' appearance that remains consistent through the material. Primarily found in Chihuahua, Mexico. For identification, look for the high-contrast black arfvedsonite spots against a lighter peralkaline background.

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