igneous
Dalmatian jasper
Orbicular quartz-rich rhyolite, commonly marketed as Dalmatian jasper
AI-generated identification · may be incorrectA polished/tumbled, cream-colored stone with black rounded spots. Typically Mohs 6.5–7, opaque, with a dull to vitreous luster; spots are commonly arfvedsonite or other dark amphibole minerals in a feldspar- and quartz-rich matrix, without obvious cleavage.
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Physical properties
A polished/tumbled, cream-colored stone with black rounded spots. Typically Mohs 6.5–7, opaque, with a dull to vitreous luster; spots are commonly arfvedsonite or other dark amphibole minerals in a feldspar- and quartz-rich matrix, without obvious cleavage.
Formation & geological history
Formed from silica-rich volcanic magma that cooled as rhyolite, with dark mineral inclusions developing during crystallization; most commercial material comes from Mexico and is geologically young compared with ancient crystalline basement rocks.
Uses & applications
Used for cabochons, beads, decorative stones, and small carvings. It is an inexpensive collector and metaphysical stone rather than a major industrial material.
Geological facts
Despite its trade name, Dalmatian jasper is generally rhyolite rather than true jasper, which is a microcrystalline variety of quartz. The spotted pattern resembles a Dalmatian dog’s coat.
Field identification & locations
Identify it by the cream rhyolitic base, irregular black spots, and hardness sufficient to scratch glass; distinguish it from Dalmatian stone imitations and spotted sedimentary rocks. Commonly found as polished pieces from Mexico.
