igneous
Dalmatian Jasper
Peralkaline rhyolite with arfvedsonite inclusions
Hardness: 5.5-7 (Mohs); Color: Creamy white to pale gray base with black spots; Luster: Vitreous to dull; Crystal structure: Trigonal/Microcrystalline; Cleavage: None
- Hardness
- 5
- Color
- Creamy white to pale gray base with black spots
- Luster
- Vitreous to dull
Identified More igneous →
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Physical properties
Hardness: 5.5-7 (Mohs); Color: Creamy white to pale gray base with black spots; Luster: Vitreous to dull; Crystal structure: Trigonal/Microcrystalline; Cleavage: None
Formation & geological history
Formed through the cooling of silica-rich volcanic magma. The characteristic black spots are inclusions of the amphibole mineral arfvedsonite. Most commercial specimens are found in Chihuahua, Mexico.
Uses & applications
Primarily used as a decorative stone, gemstone for jewelry (beads, cabochons), and in spiritual/metaphysical practices as a grounding stone.
Geological facts
Despite the trade name 'Jasper', it is technically an igneous rock (rhyolite), not a true sedimentary chalcedony. It was named for its resemblance to the Dalmatian dog breed.
Field identification & locations
Identify by its distinctive black 'polka dots' on a light-colored matrix. It is extremely popular in the gem trade due to its unique pattern and ease of polishing. It is typically found in volcanic regions.
