Where is Orbicular Jasper found?
Chalcedony (microcrystalline quartz) with various impurities
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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 type of orbicular jasper) found along the coastline, particularly in the Marovato and Kabamby regions. These deposits are often associated with ancient rhyolitic flows.
Oregon, USA
Known for various types of orbicular jasper, including 'Poppy Jasper' and other varieties with distinct orb patterns, often found in volcanic terrains.
California, USA
Deposits of orbicular jasper, sometimes referred to as 'Leopard Skin Jasper', are found in certain volcanic and sedimentary formations.
Mexico
Some regions yield orbicular jasper, often with vibrant colors and intricate patterns.
Australia
Certain areas produce orbicular jasper, though less commonly known than other localities.
Collecting tips
- Look for Volcanic and Hydrothermal Zones. Orbicular jasper often forms in association with volcanic rocks (rhyolites, tuffs) or in areas where silica-rich hydrothermal fluids have circulated. Explore ancient volcanic fields or areas with evidence of past hydrothermal activity.
- Examine Riverbeds and Alluvial Deposits. Jasper is very durable and can be transported by water. Riverbeds, gravel bars, and alluvial fans in regions known for jasper can be good places to find water-worn pebbles or cobbles of orbicular jasper.
- Check Outcrop Exposures. Look for exposed rock faces, road cuts, or mining dumps in areas with known jasper occurrences. Orbicular jasper can occur as nodules, veins, or massive beds within the host rock.
- Identify Distinctive Patterns. The key identifying feature is the spherical or eye-like patterns. Look for these distinct 'orbs' on weathered or freshly broken surfaces. Colors can be highly variable, so focus on the texture.
- Use a Hardness Test. Jasper is a form of quartz, so it will be hard (Mohs 6.5-7). It will scratch glass and steel. This helps differentiate it from softer rocks or minerals that might have similar patterns.
Quick Check
- Color:
- Highly variable (red, green, brown, yellow, white, grey, black), often multi-colored with distinct orbicular patterns.
- Luster:
- Dull to waxy, sometimes vitreous on fresh breaks.
- Streak:
- White (due to its quartz composition, even with impurities, the streak is typically white).
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