Morrison Formation Necklace
My personal favorite sedimentary rock sequence is the Morrison Formation. It's especially prevalent in the Colorado Plateau of Utah and is the source for many Dinosaur Bones and radioactive minerals such as Uranium. Not to mention, it is stunning in color: purpleish-red with white streaks. It's not quite a rock, more like a hard clay, and I found a nice piece of it to bring home and turn into a necklace as an ode to this rock unit from the Late Jurrassic.