Geodes, Thundereggs and Concretions, OH MY!

Many fascinating geological formations begin in simple ways-as mud balls, animal burrows, or gas bubbles trapped within molten rock. Over millions of years, mineral-rich fluids seep into these spaces, forming crystals and other intricate structures. This presentation for adults by Michael Hopkins from the Contra Costa Mineral and Gem Society explores how these formations develop, how they differ, and where they can be found. Topics include geodes, thundereggs, septarian nodules, concretions, and vugs.