Here are two interesting Pennsylvanian fossils that I bought at the Flagg Gem and Mineral Show in Mesa, Arizona (~4.5 inches wide) from the Apex Mine near St. George, Utah hosted in the Callville Limestone. A Chatetes sp. sponge is coated in azurite and malachite. Syringopora sp. coral molds are in goethite with significant germanium and gallium values. The goethite replaced the limestone.
See this USGS article about the mine: https://pubs.usgs.gov/bul/1577/report.pdf