sedimentary
Fossiliferous Flint or Chert with Bryozoan Fossils
Sedimentary cryptocrystalline quartz (SiO2) with fossil inclusions
Hardness of 7 on the Mohs scale, vitreous to waxy luster, conchoidal fracture, white to tan outer cortex with bluish-grey or dark interior, microcrystalline quartz structure.
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Physical properties
Hardness of 7 on the Mohs scale, vitreous to waxy luster, conchoidal fracture, white to tan outer cortex with bluish-grey or dark interior, microcrystalline quartz structure.
Formation & geological history
Formed in marine environments through the replacement of calcium carbonate sediments by silica-rich fluids millions of years ago during the Cretaceous period, often found in chalk deposits.
Uses & applications
Used historically for primitive stone tools and fire-starting; today primarily of interest to fossil and beach-combing collectors.
Geological facts
This specimen displays distinctive ring-like patterns which are fossilized colonial marine organisms such as bryozoans or sponges embedded within the flint nodule.
Field identification & locations
Commonly found along chalk cliffs and beaches (such as the southern coast of England or parts of northern Europe). Identified by its smooth water-worn pebble shape and distinct fossil impressions on the weathered surface.
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