Nobody knows for sure exactly why the rocks ring like bells when struck with a hammer is a mystery. The rocks do contain a significant amount of iron, which might be part of the explanation. However, the high iron content doesn’t explain two other strange qualities that the rocks possess . . . Not all of the rocks ring when struck, and they don’t ring when they are removed from the site, suggesting that the ringing has something to do with the way the rocks lay against one another. Larger flat ones seem to produce an especially impressive sound when struck.
Compared to the neighbors .
The Ringing Rocks are very small part (160 acres) of a mountainous region called the Boulder Batholith, which encompasses a large portion of southwestern Montana. Batholiths originate when magma cools slowly beneath the surface to form granite.
Edited by zoser, 04 February 2013 - 07:53 PM.