One is the Clay Minerals Society Glossary of Clay Science Project. An ongoing effort to compile a glossary of terms "as used in clay science". The small site also has word- and PDF-file versions for download. I find this very useful for non-native speakers (like me) because not all terms are easily translated.
The other one is more eye-pleasing. It is the Images of Clay archive of the Mineralogical Society of Great Britain and Irland and The Clay Minerals Society. This is a collection of images of (clay) minerals available for non-profit purposes, such as teaching - and I suppose blogging. I especially like the time lapse video of exfoliating vermiculite.
Image (Video) reproduced from the 'Images of Clay Archive' of the Mineralogical Society of Great Britain & Ireland and The Clay Minerals Society (www.minersoc.org/gallery.php?id=2.")