Internet sleuthing is a tricky thing. I decided to put some of my own research here to help others that might be curious about making pigments from different sources. Knowing that copper is used to produce some wonderful colors led me to explore ways to make my own pigments for painting. Clay, metal oxides, and certain plants can be processed pretty easily to make pigments. Below are some examples of easily prepared pigments that can add a unique and local touch to your work. Hopefully, the vague instructional will be helpful as you explore your own ways of making earth into pigments.
Another note on earth pigments: Baking them at higher temperatures can make them darker, allowing you to create varying shades from the same type of material.
Now comes the copper. This was interesting but tedious. It does involve using varying forms of nasty chemicals, so use appropriate caution.