igneous section here, clicking down one layer will lead you to his current metamorphic and sedimentary pages, as well -- and eventually, to the redone versions.
I chose serpentine for this photo, because
1) it's in Oakland, and Andrew also does an Oakland Geology blog, which is fascinating if you're someone like me and
2) it's my all-time favorite rock. I've got a long and fancy serpentine post sitting there in notepad waiting patiently for me to finish it for this blog.