The Contra Costa Mineral & Gem Society is considered by many the Bay Area's premier showcase of world class speakers on the earth sciences and lapidary arts. Topics are broad and varied and include geology, geophysics, photography, rock and gem properties, identification, and discovery.

Monthly meetings usually feature a speaker of notable distinction in their field. Some are experts in field collecting; some are university professors or known for their discoveries of contributions to earth science or lapidary. Some recent contributing speakers and their topics are listed below.

• Thunder Eggs with John Stockwell, rockhound, geologist, and thunder egg enthusiast. He discusses the origins and formation of thunder eggs, and how to find them. John is respected worldwide for his research. Many believe he has discovered the mysteries of their origin.

• Geology of the San Francisco Bay Area by Doris Sloan, University of California, Berkeley, and John Karachewski. Magnificent photography accompanies Doris' description of Bay Area Geology - another don't miss opportunity. Their award-winning book will be available for sale and signing. Geology & Mining History in the Mount Diablo Area with Speaker Craig Lyon, retired Chevron exploration geologist and volunteer field guide and speaker for the Mount Diablo Interpretive Association.

• Opal Prospecting: Fun and Profits for Everyone by Eileen Bower, Antioch Lapidary Club member. Eileen and her partner, describe their fascinating and lucrative first time experiences hunting for opals in the Virgin Valley. Includes opal displays by several members.

• Finding Gems - The Emerald Colors of the South Fork ; Ken Whitlatch discusses underwater explorations for Vesuvianite, Jade, and gold near the Klamath River, Oregon.

• Identifying Gems & Minerals; Analysis of Quality and Value by Barrie Bieler. Identification of loose and rough precious and semiprecious stones. Followed by a hands-on mineral identification class.

• A Scenic Tour of California Geology by John Karachewski. John's magnificent photography takes us through California as he describes the geology of our state - a don't miss opportunity.

• The Benitoite Gem Mine - Past, Present and Future by Rick Kennedy. Rick is one of the foremost collectors and experts on the state gem, Benitoite.

• Recreational Prospecting in the 21st Century. Eric Towle, experienced prospector from Delta Gold Digers in Stocton, reveals gold discovery techniques, methods, and secrets.