Specimen at a glance
| Mineral | Flint (microcrystalline quartz) |
|---|---|
| Chemistry | SiO2 |
| Mohs hardness | ~7 |
| Crystal system | Microcrystalline quartz |
| Locality | Poland |
| Form | Raw / rough |
| You receive | The exact specimen pictured |
About this specimen
A large natural flint nodule from Poland, still wearing the soft cream-white chalk cortex it formed inside. It fills a hand — a lobed, knobbly, almost organic shape with rounded protrusions and deep folds between them, the sort of form that gets flint nodules mistaken for fossils, bone or broken pottery when they turn up in a ploughed field.
Flint is microcrystalline quartz. The silica dissolved out of sponge spicules and other siliceous organisms on a Cretaceous sea floor and re-precipitated as nodules inside the accumulating chalk, filling burrows and cavities in the soft sediment — which is exactly why the outline is so lumpy. The white rind is the cortex, the weathered porous skin left where chalk met flint; on this piece it is washed through with warm ochre and gold where iron-bearing groundwater has stained it.
The third photograph shows the nodule alongside a flake of the same material so you can see what the interior looks like: dense, waxy grey-brown flint with the smooth curving conchoidal fracture surface that made this stone the sharpest cutting edge available to human beings for most of our history. Northern Europe’s chalk flint, Poland’s included, supplied Stone Age toolmaking across the continent, and Poland remains best known among collectors for the banded striped flint of the Holy Cross Mountains. The nodule is the item offered here; the flake appears in the photo for reference.
Flint is quartz, so Mohs 7 and very tough. No special care is needed — this is a display piece that can simply sit out.
Flint: the science
- Flint breaks with sharp conchoidal fractures, which is why people shaped it into tools for hundreds of thousands of years.
- Struck against steel, flint throws sparks. It was the ignition source in flintlock firearms.
- The white outer rind, called cortex, is the chalky skin left from the rock it grew inside.
Go deeper
Want the full story on flint: how it forms, how to identify it, and what makes a great specimen?
Questions about this piece
What is flint?
Flint is a dense microcrystalline quartz that forms as nodules inside chalk, where silica from sponge spicules and microscopic plankton gathered and hardened.
Where was it found?
This piece comes from Poland. We list a locality whenever it is known, because where a mineral formed is part of its story and its value.
How hard is it, and how should I care for it?
It rates ~7 on the Mohs scale. Durable, but fractured edges can be sharp. Rinse and air dry.
Is this the exact piece I will receive?
Yes. This listing was photographed individually, and you receive the exact piece shown in the photos.
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