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 More igneous →
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Physical properties
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
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.
