igneous
Dalmation Jasper
Aplite with Arfvedsonite inclusions (SiO2 with Na3(Mg,Fe2+)4AlSi8O22(OH)2)
Hardness: 6-7 (Mohs), Color: Creamy white to pale gray with black spots, Luster: Vitreous to dull, Structure: Microcrystalline, Specific Gravity: 2.6-2.7
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Physical properties
Hardness: 6-7 (Mohs), Color: Creamy white to pale gray with black spots, Luster: Vitreous to dull, Structure: Microcrystalline, Specific Gravity: 2.6-2.7
Formation & geological history
Formed from volcanic activity when magma cooling at the Earth's surface solidified rapidly, trapping black needle-like crystals of Arfvedsonite within a fine-grained feldspar/quartz matrix.
Uses & applications
Primarily used for lapidary work, jewelry (beads and cabochons), carvings, and as a popular grounding stone in metaphysical collecting.
Geological facts
Despite being marketed as a 'Jasper' (which is a sedimentary rock), it is actually a peralkaline igneous rock known as Aplite. The black spots are often mistaken for Tourmaline but are actually Arfvedsonite.
Field identification & locations
Identifiable by its distinct 'dalmatian dog' spotting pattern. Most commercial specimens are sourced from Chihuahua, Mexico. It is easy to polish and very durable.
