An agate geode is a hollow agate lined with tiny quartz crystals. Agate geodes are formed in gas bubbles in lava. After the lava hardens around the bubble, water seeps through and deposits silicates and/or carbonates on the inside surface. Over time, this allows quartz crystals to form inside the hollow chamber. Bedrock containing geodes eventually weathers and decomposes, leaving geodes present at the surface. Agate geodes are found in Mexico, Brazil, Morocco and India.
The colorless, transparent variety of quartz. Quartz is composed of silicon dioxide, the most common mineral in Earth’s crust after ice and feldspar. The name “rock crystal” emerged in the Middle Ages to differentiate it from colorless glass. The Greeks called water-color crystals krystalos, hence the name “crystal”. The name quartz comes from Old German, but its origins are unknown. Metaphysically, quartz is used for power, communication, and cleansing. Found worldwide, fine specimens of quartz can be found in Arkansas, Brazil, and Madagascar.