a fossil or other oddly shaped stone or crystal.
a stone arrowhead.
a megalith or other stone monument of ancient origin.
Origin of fairy stone
First recorded in 1785–95
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
Examples from the Web for fairy stone
I have a singularly-shaped soapstone ornament, taken from an Indian grave, whose perforation indicates the 'fairy-stone.'