Where is Oolitic Jasper found?
Oolitic Jasper (a variety of Chalcedony/Quartz)
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Open the appOolitic 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 Oolitic Jasper
United States
Found in various states, including Oregon (e.g., Biggs Jasper), Idaho, and parts of the Midwest where ancient marine sedimentary rocks are exposed.
Australia
Known from several localities, often associated with banded iron formations or other silicified sedimentary units.
South Africa
Occurrences reported in silicified sedimentary rocks.
Russia
Found in regions with extensive sedimentary rock formations.
Collecting tips
- Look for Sedimentary Environments. Focus your search in areas known for ancient shallow marine sedimentary deposits, particularly those that contain oolitic limestones or chert beds.
- Examine Outcrops and Riverbeds. Oolitic Jasper can be found in exposed rock outcrops, road cuts, and as float in riverbeds and gravel deposits downstream from its source.
- Identify Oolitic Texture. The key identifying feature is the presence of small, spherical to ellipsoidal grains. A hand lens may be useful for clearer observation of the ooids.
- Check for Hardness. Like other jaspers, Oolitic Jasper is hard (Mohs 6.5-7) and will scratch glass. This helps distinguish it from softer oolitic limestones.
Quick Check
- Color:
- Variable (red, brown, yellow, green, gray), often with contrasting ooids.
- Luster:
- Dull to waxy.
- Streak:
- White.
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