I'm not sure these really are particularly mysterious. The rock resonates when struck in the same way than bells do. This is true of glass, metal and some cryst

I'm not sure these really are particularly mysterious. The rock resonates when struck in the same way than bells do. This is true of glass, metal and some crystals obviously so it doesn't require any strange mechanism to work in rocks as long as presumably the rock has a particular consistency and shape and you can hold it in such a way that it can resonate without you clamping the vibrations. Musical stones or rocks are known in many places around the world. Here are some examples: Africa - http://www.namibian.org/travel/archaeology/musical-stone.html http://www.namibian.org/travel/archaeology/musical-stone.htm... UK - https://www.neatorama.com/2007/01/28/the-original-rock-music-stones-that-sing/ https://www.neatorama.com/2007/01/28/the-original-rock-music... Stalactites often resonate beautifully when struck with a soft mallet. I've been in caves in France and in Africa where tour guides demonstrated this phenomenon. Here's a recording of music played on a rock sculpture specifically designed to be playable like a xylophone -https://www.amazon.com/Music-Stones-Stephan-Micus/dp/B000025ZXK https://www.amazon.com/Music-Stones-Stephan-Micus/dp/B000025... This one is pretty cool, because it explains how a particular set of musical pillars in India were constructed so they play a scale. http://www.phenomenalplace.com/2017/09/musical-pillars-at-hampi-india-how-do.html http://www.phenomenalplace.com/2017/09/musical-pillars-at-ha...