I'm starting to evaluate the wild clay in my yard in Maple Grove, MN. I've floated off the organic material, and sieved it with a paint strainer bag. It bisqued up nicely, but melted into bubbly baby-poo green at cone 6.
I'm not expecting to make great art with this, just making a statement about how crappy my garden soil is, and get an intuitive understanding of how clay is processed and tested.
My next step is to try it at cone 1 to see if I can use it as earthenware, and maybe try it as a slip over a high-fire clay body.
I have 2 pieces that I'm going to raku fire on Thursday, weather permitting. If it can take bisque it can take raku.