igneous
Dalmatian Stone (Dalmatian Jasper)
Peralkaline Quartz-Feldspar Porphyry with Arfvedsonite
Hardness: 5.5-7 (Mohs scale); Color: Cream or beige base with black spots; Luster: Vitreous to dull; Crystal structure: Trigonal/Monoclinic (mixed); Specific gravity: ~2.6-2.7
- Hardness
- 5
- Color
- Cream or beige base with black spots
- Luster
- Vitreous to dull
Identified More igneous →
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Physical properties
Hardness: 5.5-7 (Mohs scale); Color: Cream or beige base with black spots; Luster: Vitreous to dull; Crystal structure: Trigonal/Monoclinic (mixed); Specific gravity: ~2.6-2.7
Formation & geological history
Formed through the cooling of silica-rich magma (igneous). The black spots are needle-like inclusions of the amphibole mineral Arfvedsonite. Most commercial specimens are sourced from Chihuahua, Mexico.
Uses & applications
Primarily used for lapidary work, jewelry (beads, cabochons), carvings, and as a popular collector's stone due to its unique pattern.
Geological facts
Despite being called 'jasper' in the trade, it is not a variety of microcrystalline quartz; it is technically an igneous rock primarily composed of quartz and feldspar.
Field identification & locations
Identify by its distinct spotted appearance resembling a Dalmatian dog breed. It is exclusively found in Mexico. In the field, look for a fine-grained light matrix with regular dark amphibole inclusions.
