sedimentary
Chert (Heart-shaped Pebble)
Cryptocrystalline quartz (SiO2)
Hardness: 7 on Mohs scale; Color: Tan to light grey; Luster: Dull to waxy; Crystal structure: Trigonal (microscopic); Cleavage: None (conchoidal fracture); Specific gravity: 2.65.
- Hardness
- 7 on Mohs scale
- Color
- Tan to light grey
- Luster
- Dull to waxy
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Physical properties
Hardness: 7 on Mohs scale; Color: Tan to light grey; Luster: Dull to waxy; Crystal structure: Trigonal (microscopic); Cleavage: None (conchoidal fracture); Specific gravity: 2.65.
Formation & geological history
Formed through the precipitation of silica from seawater or the replacement of limestone by silica-rich fluids. This specimen was likely weathered and smoothed into its current shape by fluvial or glacial action.
Uses & applications
Commonly used as gravel, road surfacing, or abrasive media. Historically used for making tools like arrowheads due to its sharp edges when broken.
Geological facts
Chert is remarkably durable and resistant to chemical weathering. Heart-shaped 'love rocks' are popular finds for beachcombers and casual collectors due to their pareidolian appeal.
Field identification & locations
Identify in the field by its hardness (it will scratch glass) and its smooth, rounded texture from water erosion. Found in sedimentary basins and riverbeds worldwide.
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