Here are some pretty good images of clay from the Clay Minerals Society:
http://www.minersoc.org/pages/gallery/claypix/index.html
You can also access their journal articles from 1952-2001 for free, here:
http://www.clays.org/JOURNAL/archive/TOC/main.htm
At another site you can access for free the journal articles of the Mineralogical Magazine, from 1876-1999:
http://rruff.geo.arizona.edu/doclib/MinMag/TOC/main.htm
Clay science is progressive and has its own history, much like we have our own history of pottery. Views change and expand as new information comes to light. This is particularly true for us, for example, with reference to what is known about cristobalite and its occurrence.
I was looking to see if anyone supplied cookeite, a blue to green lithium chlorite clay, when I came across the Clay Minerals Society web page. Cookeite can be found in Arkansas, Maine, and Connecticut. My native clays will often contain chlorite clays but of the more common varieties.
Cookeite: http://www.minerals.net/mineral/cookeite.aspx
I hope everyone has a nice week!
Marian
Neon-Cat Ceramics
www.neon-cat.com