The first genetic classification of jaspers (by M. Campos-Venuti 2010).
3-JASPERS ON FOSSILS
Jaspers on fossils are pseudomorphosis of silica on variable organogenic material.
Fossil tree, Mahajunga, Madagascar.
A fossil dinosaur bone from the region between Utah and Colorado around Dinosaur National Monument.
Fossil coral, Sumatra, Indonesia.
Mary Ellen Stromatolite Jasper (Collenia Undosa), Biwabik Iron Formation, Northern Minnesota.
Turritella Jasper, Delaney's Rim area, Wamsutter, Wyoming.
much more in the Marco Campos-Venuti book:
"Genesis and Classification of Agates and Jaspers: a New Theory"
that you can buy here.