Moss Opal in Red Hills Recreation Area (BLM). 

Example opal: https://www.mindat.org/photo-701949.html

Rules for rockhounding on BLM land: https://www.blm.gov/programs/recreation/rockhounding#:~:text=BLM's%20regulations%20(43%20CFR%208365.1,on%20BLM%2Dmanaged%20public%20lands.