Fossils and gypsum from road cut

Ever see a fossil in a crystal?

Crinoid stem in gypsum found at... paste 32°44'47.22"N 98°32'5.52"W into google maps or if that doesn't work right... a road cut on highway 180 between Brad and Caddo, Texas. (Which is about an hour west of Fort Worth for quick context.) There is also a fossil park outside of mineral wells which has the same sorts of fossils and no traffic but requires digging.

Weak bonding caused by fast forming layers of gypsum. These crystals probably formed over a matter of months to a few years in the erosion of the road cut as mineral rich water came out of the ground and was met with intense Texas heat as opposed to crystals that take 100's too millions of years to form. These crystals are fragile and can literally be dissolved by boiling them for a day or two if you fancy wasting that much of your time.

Sure is pretty though.

ooooo shiny

A varied sample of what I pulled from the surface at the above mentioned road cut. a little warm water a scrub brush and a mild acid (vinegar, lemon juice, or diluted muriatic acid for pools are good and easy to come by) May my wife's ugly green hand towels rest in piece. Muhahahaha! ... I bought her knew ones to apologize.

Small corals, crinoid stems and fragments, and gastropods make the bulk of the fossils. Shark teeth, echinoid (prehistoric sea urchins ... cidarid and Phyllacanthus sp. mostly) spines and segments, belemnites (as described by my my son when he was 9 ~ squid wearing a pointy hat), small ammonites, turrilites (sort of a pig tail ammonite) are also preasent.

As are bivalves... forgot those... And probably more that are slipping through the cracks in what I call my brain.

These fossils in this last image are from south of the above road cut. From one just north of lake Brownwood on FM 2273. Now there are also large rugose corals in greater abundance as well as much larger belemnites.

Calcified horn coral slice

This is a cross cut from a rugose coral. I don't recall if it came from one of those or further south but it is typical of the above corals internal appearance. If you zoom you can plainly see the structure of the coral as it would have been roughly, before fossilization. Specifically the minerals involved in replacing the organic matter of the coral are calcite, trace amounts of iron and sulfur, and limestone which is a rock comprised primarily of calcium carbonates like calcite.