igneous

Dalmation Stone (often called Dalmatian Jasper)

Peralkaline Rock (Microgranite/Aplite), SiO2 with inclusions of Arfvedsonite

Hardness: 6-7 (Mohs); Color: Pale gray, cream, or beige with distinct black circular spots; Luster: Vitreous to dull; Crystal structure: Trigonal/Monoclinic inclusions; Cleavage: None; Specific Gravity: 2.6-2.7

Hardness: 6-7 (Mohs)
Luster: Vitreous to dull

Identified March 8, 2026More igneous →

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Physical properties

Formation & geological history

Formed from the cooling of peralkaline magma. The black spots are needle-like inclusions of Arfvedsonite (an amphibole mineral) rather than Tourmaline as commonly misidentified. Most geological ages for these deposits are Mesozoic to Cenozoic.

Uses & applications

Primarily used for lapidary work, cabochons, beads for jewelry, tumbled stones for collectors, and decorative carvings.

Geological facts

Despite being marketed as 'Jasper' (a sedimentary chalcedony), it is actually an igneous rock. It is named for its visual resemblance to the coat of a Dalmatian dog.

Field identification & locations

Identify by its opaque white/cream background and uniform, distinct black spots. It is almost exclusively found and mined in Chihuahua, Mexico. Collectors should look for high contrast between the base color and the spots.

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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