Does anyone on here know anything about rocks? There is an area where I find rocks that have a hard outer box with a core of clay. Here is a photo of one I am cleaning up
These rocks are usually blocks and not round rocks. The outer shell is about an inch thick and thicker. If the rock has been broken and is lying in the woods the center will look the same color as the outer rock. The center is some type of red/gold colored clay. It is very hard but is dissolves in water. I collect these rocks, clean them out and use them as planters. Can anyone tell me how this type of rock formed? I am curious how the outer shell can be a stone and the inner substance can be clay.
