I read three books: Gold Fever by Verla Kay to go with the mining activity, A Rock is Lively by Diana Hutts Aston, and If Rocks Could Sing by Leslie McGuirk. I did introduce the California Gold Rush era a little bit to give some historical context as the age range for this program is 5-12. Most of the attendees were in the middle of that range. This book has some great cross-curriculum uses in a school setting as it is written in rhyme. Worth checking out if you can track down a copy.
I had a lot of fun with this program series and plan to offer it again next summer!
*Earth Science Week is October 9-15 in 2016.