Extracting microfossils from flint
by Joe Shimmin
Flint meal is a rich source of silaceous microfossils. The material is often packed with sponge spicules as well as foraminifera and ostracods.
To collect flint meal unweathered, fresh flints recently eroded out of chalk are necessary. Some locations will have a higher concentration of meal bearing flint nodules but when you are at a chalk location, it is always worth keeping an eye out for the ‘right type’ of flint.
Flint meal bearing flint nodules tend to have a pitted and uneven appearance. When broken, cavities inside the rock can be seen, and in these cavities a powdery chalk like substance can sometimes be found – this is flint meal.
Once you have collected a quantity of this material, place it into acid to remove its calcium carbonate content and then wet sieve it through 2mm, 250 micron and 150 micron sieves.
When dry, you should be able to find many different types of sponge spicules in your residue, together with other types of microfossils. These can then be mounted on microfossil slides available from UKGE using a 20% PVA in water solution.
Endecotts Test Sieves Available from UKGE