Where is Orbicular Jasper found?
Chalcedony (microcrystalline quartz) with various mineral inclusions
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Open the appOrbicular Jasper occurs in specific geological environments. Knowing where to look, and in what kind of rock, is the difference between going home empty-handed and finding a great specimen.
Where to find Orbicular Jasper
Madagascar
Famous for 'Ocean Jasper,' a specific variety of orbicular jasper found along the northwestern coast. It is known for its vibrant colors and distinct orb patterns, often associated with rhyolitic volcanic rocks.
United States (Oregon, California)
Various localities produce orbicular jaspers, often associated with volcanic formations. For example, Biggs Jasper from Oregon, though not strictly orbicular, exhibits similar patterns. Specific orbicular jaspers are found in localized deposits.
Mexico
Some deposits of orbicular jasper have been reported, often with unique colorations and patterns.
Egypt
Historical sources mention jasper varieties, and some may exhibit orbicular characteristics, though less commonly known than other localities.
Collecting tips
- Geological Context. Focus searches in areas with known volcanic activity (especially rhyolitic) or sedimentary formations that have undergone significant hydrothermal alteration. Look for outcrops of chert, jasper, or altered volcanic rocks.
- Weathered Outcrops and Alluvial Deposits. Orbicular jasper is often found as nodules or cobbles in weathered outcrops or in stream beds and alluvial fans downstream from primary deposits, as it is resistant to weathering.
- Color and Pattern Recognition. Train your eye to recognize the characteristic spherical or concentric patterns and the wide range of colors. Freshly broken surfaces might reveal the internal structure better than weathered exteriors.
- Hardness Test. Jasper is hard (Mohs 6.5-7). If you suspect a find, try to scratch it with a steel knife (hardness ~5.5). If it doesn't scratch, it's likely a quartz-based material.
Quick Check
- Color:
- Multi-colored with distinct spherical or concentric patterns.
- Luster:
- Dull to waxy.
- Streak:
- White (due to the dominant quartz component).
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