he rock isn’t lit from behind, and it isn’t see-through. It, along with others, seems as though it is lighting up internally. For centuries, this internal glow has stumped people, until a combination of geology and physics provided a clue to what is known as the Schiller Effect today, and more about it can be found by taking the time to visit this website.
https://www.livescience.tech/2019/10/09/what-is-the-schillers-effec...