metamorphic
Whetstone
Novaculite / Microcrystalline Quartz
AI-generated identification · may be incorrectHardness of 7 on the Mohs scale, typically gray or brown, with a dull to waxy luster and dense cryptocrystalline structure.
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Physical properties
Hardness of 7 on the Mohs scale, typically gray or brown, with a dull to waxy luster and dense cryptocrystalline structure.
Formation & geological history
Formed through the diagenesis and low-grade metamorphism of ancient marine silica-rich deposits over hundreds of millions of years.
Uses & applications
Used historically and presently as an abrasive tool for sharpening edged metal instruments like knives and tools.
Geological facts
Arkansas novaculite is world-famous for producing some of the highest-quality natural sharpening stones known.
Field identification & locations
Identified by its fine-grained texture, ability to scratch glass, and smooth feel resulting from water tumbling or cutting.
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