Are the rocks ethically sourced?

All rocks sourced from private property and licensed commercial operations. No collection from public or protected lands.

Good point.

“All park resources are protected so that all visitors may enjoy them. It is against the law to remove any of the natural (petrified wood, other rocks, plants, animals) or cultural resources (pottery pieces, arrowheads, Route 66 debris), including picking flowers.”

https://www.nps.gov/pefo/faqs.htm