sedimentary
Amber Flint (Chert)
Cryptocrystalline Quartz (Silicon Dioxide, SiO2)
Hardness: 6.5-7 on Mohs scale. Color: Honey-yellow, amber, and milky white (calcareous cortex). Luster: Waxy to vitreous. Structure: Microcrystalline with no visible crystals. Fracture: Conchoidal (shell-like curves).
- Hardness
- 6
- Color
- Honey-yellow, amber, and milky white (calcareous cortex)
- Luster
- Waxy to vitreous
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Physical properties
Hardness: 6.5-7 on Mohs scale. Color: Honey-yellow, amber, and milky white (calcareous cortex). Luster: Waxy to vitreous. Structure: Microcrystalline with no visible crystals. Fracture: Conchoidal (shell-like curves).
Formation & geological history
Formed as nodules within chalk or limestone deposits, typically during the Cretaceous period (approx. 66-145 million years ago). It originates from the precipitation of silica from seawater or the silica-rich remains of marine organisms like sponges and diatoms.
Uses & applications
Abrasives, construction aggregate, and historical use for tool-making (lithics). Polished specimens are used in lapidary work, jewelry, and as decorative pocket stones.
Geological facts
This specimen features a well-preserved 'cortex,' which is the white, chalky outer layer formed by the interaction between the silica nodule and the surrounding limestone matrix. In ancient times, flint was the primary material for fire-starting and weaponry.
Field identification & locations
Identify in the field by its sharp, glass-like edges when broken and its characteristic white rind. Often found in riverbeds, coastal beaches near chalk cliffs (like the UK or Northern France), or gravel pits. Collectors look for the unique amber-honey translucent color banding shown here.
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