sedimentary
Wonderstone Jasper
Silicon Dioxide (SiO2) with iron oxide inclusions
Hardness: 6.5-7 (Mohs); Color: Banded patterns of cream, red, brown, and black; Luster: Waxy to dull; Crystal structure: Microcrystalline; Cleavage: None (conchoidal fracture); SG: 2.6
- Hardness
- 6
- Color
- Banded patterns of cream, red, brown, and black
- Luster
- Waxy to dull
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Physical properties
Hardness: 6.5-7 (Mohs); Color: Banded patterns of cream, red, brown, and black; Luster: Waxy to dull; Crystal structure: Microcrystalline; Cleavage: None (conchoidal fracture); SG: 2.6
Formation & geological history
Formed from volcanic ash deposits (rhyolitic tuff) that were altered by hydrothermal fluids or groundwater, resulting in rhythmic banding of iron oxide minerals. Most famous deposits are Miocene in age.
Uses & applications
Primarily used for lapidary work, including cabochons for jewelry, decorative carvings, bookends, and collection displays.
Geological facts
The unique rhythmic banding is often a result of Liesegang rings, which are chemical precipitates formed during the weathering process of the volcanic tuff.
Field identification & locations
Look for distinct, concentric or fluid-like bands of color within a dense, fine-grained rock. Commonly found in the Western United States, particularly Utah and Nevada.
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