3.5" Las Choyas "Coconut" Nodule with Agate - Mexico

Geodes are rounded, hollow voids in rocks filled with crystals and other minerals. They typically form when air bubbles inside of volcanic rock form hollow cavities. Over time, as mineral-rich water seeps into the rock, those minerals deposit tiny crystals on the sides those hollow cavities. After millions of years, the flow of water gradually builds crystals inside the empty space.

Las Choyas geodes, often referred to as coconut geodes, are mined from 100 to 200 feet below the surface near Chihuahua, Mexico. Shafts are drilled down to the geode-bearing white clay, and then tunnels are dug horizontally to extract the geodes.

The geodes typically range from about 2-6 inches in diameter and can contain a variety of minerals and crystals. Most hollow geodes contain a variety of quartz, ranging from clear quartz to smoky quartz to rarer amethyst. Many secondary minerals, such as goethite, hematite, mordenite, calcite and galena, may also be present in some geodes.