http://www.unexplainedearth.com/ringing.phpIn Upper Black Eddy, Pennsylvania lies a field of boulders that just won't keep quiet. Known as Ringing Rocks Park, this jumble of enigmatic stones has perplexed researches for decades because of the melodious tones the rocks produce when struck with a hammer or any solid instrument.
Rocks that ring while fun and intriguing are not by themselves that anomalous. The musical qualities of certain types of stone have been recognized for thousands of years. For instance, the Egyptians used large slabs of basalt to produce a sort of giant xylophone.1 However, this particular field exhibits a number of unusual qualities that when taken together add up to a first class mystery. [continued]
Well, I don't about about any mystery but an interesting site nonetheless.