igneous
Dalmatian Stone
Peralkaline rhyolite with arfvedsonite (formerly incorrectly called Dalmatian Jasper)
Hardness: 5.5-7 (Mohs scale); Color: Pale gray, cream, or beige base with black or dark brown spots; Luster: Vitreous to dull; Crystal structure: Microcrystalline; Cleavage: None
- Hardness
- 5
- Luster
- Vitreous to dull
Identified More igneous →
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Physical properties
Hardness: 5.5-7 (Mohs scale); Color: Pale gray, cream, or beige base with black or dark brown spots; Luster: Vitreous to dull; Crystal structure: Microcrystalline; Cleavage: None
Formation & geological history
Formed from the slow cooling of silica-rich peralkaline rhyolite magma, which allows for some crystal grouping. The dark spots are typically crystals of arfvedsonite or other amphiboles.
Uses & applications
Primarily used for decorative carvings, cabochons, metaphysical beads, jewelry, and ornamental animal figurines.
Geological facts
Despite being marketed as 'Jasper' for years, scientific analysis shows it is an igneous rock (rhyolite), not a sedimentary jasper. The black spots are not tourmaline as often claimed, but rather the mineral arfvedsonite.
Field identification & locations
Identify by its unique 'spotted' appearance resembling a Dalmatian dog. Found predominantly in Chihuahua, Mexico. Collectors should look for even distribution of spots and high-quality polish.
