igneous
Dalmatian jasper
Orbicular rhyolite, commonly marketed as Dalmatian jasper; quartz–feldspar volcanic rock with dark aegirine/arfvedsonite-like inclusions
AI-generated identification · may be incorrectTypically cream to beige with rounded black to brown spots, opaque, fine-grained, and weakly vitreous to dull; hardness about 6.5–7 Mohs, no obvious cleavage, and specific gravity roughly 2.5–2.7. The pictured piece appears polished and tumbled.
Identified More igneous →
Explore Dalmatian jasper in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Typically cream to beige with rounded black to brown spots, opaque, fine-grained, and weakly vitreous to dull; hardness about 6.5–7 Mohs, no obvious cleavage, and specific gravity roughly 2.5–2.7. The pictured piece appears polished and tumbled.
Formation & geological history
Formed as silica-rich volcanic lava cooled, with dark mineral-rich orbicules or inclusions developing in the rhyolitic groundmass; it is principally associated with Jurassic volcanic rocks of Chihuahua, Mexico, although trade material can vary. Geological age depends on the deposit.
Uses & applications
Used primarily for cabochons, beads, carvings, polished stones, and lapidary collections; it has little structural or industrial use. Market value is generally modest, based on pattern and polish.
Geological facts
Despite its commercial name, Dalmatian jasper is usually not true jasper, because it is commonly rhyolite rather than microcrystalline quartz. Its spotted appearance resembles a Dalmatian dog’s coat.
Field identification & locations
Identify it by the cream volcanic matrix, irregular rounded dark inclusions, and low translucency; a glassy conchoidal fracture or uniform dyed spots may indicate imitation. Commonly sold from Mexico through lapidary and metaphysical-stone markets.
