igneous
Dalmatian Jasper
Peralkaline rhyolite
Hardness: 5.5-7 (Mohs); Color: Creamy grey-beige with black spots; Luster: Dull to vitreous; Crystal structure: Microcrystalline; Specific gravity: Approx 2.6
- Hardness
- 5
- Color
- Creamy grey-beige with black spots
- Luster
- Dull to vitreous
Identified More igneous →
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Physical properties
Hardness: 5.5-7 (Mohs); Color: Creamy grey-beige with black spots; Luster: Dull to vitreous; Crystal structure: Microcrystalline; Specific gravity: Approx 2.6
Formation & geological history
Formed through the cooling of silica-rich magma that contains arfvedsonite. It is primarily an igneous rock rather than a true sedimentary jasper. Most specimens are sourced from Chihuahua, Mexico.
Uses & applications
Predominantly used for lapidary work, including tumbled stones, beads, cabochons, and decorative carvings. It is popular in the crystal healing community and as an affordable jewelry stone.
Geological facts
Despite its common trade name including 'Jasper', geological testing has revealed that the black spots are actually the mineral arfvedsonite rather than tourmaline or hematite as previously thought.
Field identification & locations
Identify by the distinct cream-colored matrix with black polka-dot inclusions. In the field, look for volcanic rhyolitic deposits. Collectors should look for high contrast and smooth finish in tumbled pieces.
