igneous
Dalmatian Jasper (Dalmatian Stone)
Peralkaline rhyolite
Hardness: 5.5-7 (Mohs); Color: Pale grey or cream with black/brown spots; Luster: Dull to sub-vitreous; Structure: Microcrystalline; Specific Gravity: 2.5-2.7
- Hardness
- 5
- Color
- Pale grey or cream with black/brown spots
- Luster
- Dull to sub-vitreous
Identified More igneous →
Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 5.5-7 (Mohs); Color: Pale grey or cream with black/brown spots; Luster: Dull to sub-vitreous; Structure: Microcrystalline; Specific Gravity: 2.5-2.7
Formation & geological history
Formed through the cooling of silica-rich peralkaline magma. Despite its common name, it is an igneous rock (rhyolite) rather than a true sedimentary jasper. The black spots are typically composed of arfvedsonite or other amphiboles.
Uses & applications
Primarily used in jewelry making for beads, cabochons, and tumble stones. Also popular in gemstone collecting and metaphysical practices.
Geological facts
It is named for its resemblance to the Dalmatian dog breed. The 'spots' were long thought to be tourmaline, but scientific analysis identified them as arfvedsonite.
Field identification & locations
Identify by its distinctive black-on-white/cream spotted pattern and smooth, fine-grained texture. It is almost exclusively sourced from Chihuahua, Mexico.
More like this
Other igneous specimens
Blue Apatite
Fluorapatite (Ca5(PO4)3F)
mineral
Dark Igneous Rock (Likely Basalt or Diabase)
Basalt (extrusive igneous rock) or Diabase (intrusive igneous rock - also known as Dolerite), largely composed of plagioclase feldspar, pyroxene (augite), and sometimes olivine and amphibole. Exact mineralogy would require thin section analysis.
Igneous
Magnetite
Iron(II,III) oxide (Fe3O4)
mineral
Sodalite
Sodalite - Na8(Al6Si6O24)Cl2
mineral
Blue Apatite
Apatite (Group), Ca5(PO4)3(F,Cl,OH)
mineral
Magnetite
Magnetite (Fe3O4)
mineral