igneous
Dalmatian Jasper
Peralkaline Quartz-Feldspar Rock with Arfvedsonite
Mohs hardness: 5.5-7; Color: White to cream background with black or brownish spots; Luster: Vitreous to dull; Crystal structure: Microcrystalline; Cleavage: None.
- Hardness
- 5
- Color
- White to cream background with black or brownish spots
- Luster
- Vitreous to dull
Identified More igneous →
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Physical properties
Mohs hardness: 5.5-7; Color: White to cream background with black or brownish spots; Luster: Vitreous to dull; Crystal structure: Microcrystalline; Cleavage: None.
Formation & geological history
Formed by the cooling of silica-rich magma that produced a mixture of quartz and feldspar, with iron-rich minerals crystallizing as spots. Primarily sourced from Chihuahua, Mexico.
Uses & applications
Used extensively in lapidary work for cabochons, beads, carvings, and tumbled stones for jewelry and decorative items.
Geological facts
Despite being called 'Jasper', it is technically an igneous rock rather than a variety of chalcedony. The black spots are often identified as arfvedsonite or tourmaline.
Field identification & locations
Identified by its distinctive black spots on a light background, resembling a Dalmatian dog's coat. Collectors should look for a smooth, matte to waxy polish in tumbled specimens.
