Lithophone
en.wikipedia.org
en.wikipedia.org
Unfortunately that article gives zero explanation of how certain rocks can produce resonant tones that sound like metal, but another one does, specifically that the rocks need to be under internal stresses, analogous to a tightened guitar string: [1]
"...it does suggest strongly that the ringing ability is a direct result of internal stresses. ... A possible source of the stresses would likely be the loading stresses from the time when the rock crystallized. ... This "relict stress" theory implies that the ringing rock boulders act much like a guitar string. When a guitar string is limp it does not resonate, but a plucked string will provide a range of sounds depending on the level of applied tension. Likewise, a ringing rock boulder will only emit a dull thud if the boulder is de-stressed; however, boulders will resonate at various frequencies depending on the level of residual stress."
[1] https://en.wikipedia.org/wiki/Ringing_rocks#Ringing_ability
[1] https://en.wikipedia.org/wiki/Great_Pyramid_of_Giza#King's_C...
[2] https://www.youtube.com/watch?v=2ZmyGavbgLE&list=PLPtysUSalP...