Author Patti Polk is recognized as one of the top agate collectors in the world (as noted in the highly respected reference book Agates III by Johann Zenz). Author of Collecting Rocks, Gems and Minerals, Polk has been collecting, cutting and polishing rocks for jewelry and display for more than 20 years. She has been published in Rock & Gem magazine and numerous other periodicals; she speaks at rock and mineral club programs and frequently serves as a trail guide for visitors to Arizona.