So... here you go. Polished, tumbled rocks, for sale at a Lake of the Ozarks' cave tourist shop. I am out of town there, at a professional conference. No time to do much more. :) I was surprised at their bright colors and tones.
10/1/2020: Finished year 7 (!), with continuing gratitude towards this amazing community. Based in St. Louis, MO. Regular worker-bee and self-taught photography dilettante....
when my youngest was 5 or 6 she had a huge collection of these she purchased one at a time wherever we went. I think they reside in her potted plants now.