Description
This is a form of chert that was formed when calcium carbonate in limestone was chemically replaced by silica-rich groundwater forming layers green and rust colors.
When the layers are cut parallel to the layers of colors create an interesting pattern that resembles an old map.
While the green coloration may come from any number of minerals, both the green and orange colors are likely to be caused by iron.
Click here to see what this looked like when it was slabbed.
