Delaware mineralogical society

A Delaware 501(c)(3) non-profit earth-science educational organization


"Geodes" by Nathan Harrison

A mineral article linked to our March 5-6, 2016 Show Exhibit of the same name

What is a Geode?

"A geode is a rock containing a cavity lined with crystals or other mineral matter." (Merriam-Webster Dictionary,

"They are formed in the bubbles in volcanic rock or as animal burrows, tree roots, or mud balls in sedimentary rock. Over time, the outer shell of the spherical shape hardens, and water containing silica precipitation forms on the inner walls of the hollow cavity within them." They are found throughout the world. (DesertUSA,





Photos by Ken Casey ©2016