igneous
Basalt with Chert or Jasper Inclusion
Igneous basalt / sedimentary chert nodule
Hardness: 6-7 on Mohs scale (for quartz/chert portions) and 5-6 for basalt matrix. Color: Brownish-tan weathering crust with deep black patches. Luster: Vitreous to dull. Crystal structure: Microcrystalline/cryptocrystalline.
- Color
- Brownish-tan weathering crust with deep black patches
- Luster
- Vitreous to dull
Identified More igneous →
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Physical properties
Hardness: 6-7 on Mohs scale (for quartz/chert portions) and 5-6 for basalt matrix. Color: Brownish-tan weathering crust with deep black patches. Luster: Vitreous to dull. Crystal structure: Microcrystalline/cryptocrystalline.
Formation & geological history
Formed via volcanic activity (basalt lava flows) combined with aqueous deposition of silica-rich sediments (chert) in marine environments over millions of years.
Uses & applications
Used primarily as an educational geological specimen, or decorative landscaping stone when found in larger quantities.
Geological facts
Water-worn pebbles like this are commonly found along riverbeds or coastlines where wave action and tumbling smooth out sharp edges, revealing contrasting mineral inclusions.
Field identification & locations
Look for smooth, rounded pebbles along beaches or riverbanks that show striking color contrasts between a weathered outer rind and darker interior minerals. Common in glacial till and alluvial deposits worldwide.
