I found this rock in a river bed, it has sort of seems all over it as you can see in the picture. It is nearly perfectly circular and is about 6cm in width. It's heavy like a lump of iron.
It's almost certainly a septarian nodule, a concretion formed at the bottom of an ancient sea. Becuase yours sounds like it's heavy it may be composed of iron minerals such as limonite.
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What is this rock?
Submitted by Joelcav on Fri, 07/13/2012 - 23:30.I found this rock in a river bed, it has sort of seems all over it as you can see in the picture. It is nearly perfectly circular and is about 6cm in width. It's heavy like a lump of iron.