sedimentary
Chert (Novaculite Variety)
Microcrystalline Quartz (SiO2)
Hardness: 7 (Mohs); Color: White to light tan; Luster: Waxy to dull; Crystal structure: Cryptocrystalline (Triagonal); Cleavage: None (conchoidal fracture); Specific gravity: 2.65
- Hardness
- 7 (Mohs)
- Color
- White to light tan
- Luster
- Waxy to dull
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Physical properties
Hardness: 7 (Mohs); Color: White to light tan; Luster: Waxy to dull; Crystal structure: Cryptocrystalline (Triagonal); Cleavage: None (conchoidal fracture); Specific gravity: 2.65
Formation & geological history
Formed through the recrystallization of silica-rich marine sediments or the replacement of limestone. It typically dates back to the Devonian and Mississippian periods in major North American deposits.
Uses & applications
Historically used for stone tools (arrowheads). Modern uses include high-quality abrasive whetstones for sharpening blades, and as decorative stone in landscaping.
Geological facts
Novaculite is a specific type of chert famous in the Ouachita Mountains of Arkansas; it was a critical resource for Native American tribes who traded it across North America for its sharp edges.
Field identification & locations
Identify in the field by its hardness (will scratch glass), fine-grained texture, and sharp edges where it breaks. Commonly found in mountainous regions with folded sedimentary layers. Collectors should look for waxy translucent edges.
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