igneous
Dalmatian jasper
Dalmatian stone; commonly a leucocratic alkali-feldspar-rich igneous rock with arfvedsonite or aegirine inclusions
AI-generated identification · may be incorrectHardness about 6–7 Mohs; cream to pale gray matrix with distinctive black spots, opaque, matte to mildly vitreous when polished, and granular with no prominent cleavage. The black markings are dark amphibole/pyroxene-group minerals rather than true jasper in many commercial specimens.
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Physical properties
Hardness about 6–7 Mohs; cream to pale gray matrix with distinctive black spots, opaque, matte to mildly vitreous when polished, and granular with no prominent cleavage. The black markings are dark amphibole/pyroxene-group minerals rather than true jasper in many commercial specimens.
Formation & geological history
An uncommon alkaline igneous rock formed by crystallization of silica-poor magma, generally associated with volcanic or subvolcanic bodies; its precise geological age varies by locality. Commercial material is especially associated with Mexico.
Uses & applications
Used for tumbled stones, cabochons, beads, carvings, and decorative objects; it has modest jewelry and lapidary value rather than major gemstone value.
Geological facts
Despite the trade name “jasper,” much Dalmatian stone is not technically sedimentary jasper. Its spotted appearance resembles a Dalmatian dog’s coat.
Field identification & locations
Identify it by the cream matrix and irregular, sharply contrasting black inclusions; test cautiously because similar spotted rocks and dyed materials occur. Common sources include Chihuahua, Mexico, with additional look-alikes from other alkaline-rock localities.
