For years, decaying rocks near her home made entertaining friends outdoors a potentially embarrassing situation for Jackie Felber.

As guests were confronted with a noxious smell that seemed to come out of nowhere, they would typically fall silent, assuming a human source.

Felber would quickly explain that the stench was coming from organic rock deep beneath the scenic, mineral-rich hills above her home.

"They're like, 'sure,' " Felber said.

Believable or not, Felber was telling the truth.