Where is Botryoidal Chalcedony with Marcasite found?
SiO2 (Chalcedony) and FeS2 (Marcasite)
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Open the appBotryoidal Chalcedony with Marcasite 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 Botryoidal Chalcedony with Marcasite
Midwestern United States (e.g., Illinois, Missouri)
Known for marcasite concretions and nodules, sometimes associated with chalcedony in sedimentary formations.
Various worldwide localities
Chalcedony is ubiquitous, and marcasite can be found in many sedimentary and hydrothermal environments. Specific occurrences of this combination are less common but can be found in areas with silica-rich fluids and iron-sulfide deposition.
Collecting tips
- Look in sedimentary environments. Search in areas with shale, limestone, or sandstone, particularly where concretions or geodes are known to occur.
- Check for vugs and cavities. Botryoidal forms often line open spaces within rocks where mineral-rich fluids could precipitate.
- Be aware of Marcasite's instability. Marcasite can oxidize in humid air, forming sulfuric acid and iron sulfates. Specimens should be stored in dry, sealed containers to prevent degradation. Handle with gloves.
Quick Check
- Color:
- Variable for chalcedony (white, gray, blue, brown); pale brass-yellow to silvery-white for marcasite.
- Luster:
- Waxy to dull for chalcedony; metallic for marcasite.
- Streak:
- White for chalcedony; greenish-black to brownish-black for marcasite.
Explore Botryoidal Chalcedony with Marcasite
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