Specimens of quartz geodes from Chihuahua, Mexico. These geodes are often referred to as La Choya geodes or coconut geodes, the quartz crystals within them may be clear or smoky and are often accompanied by brown calcite and agate. Geodes form as bubbles of gas within magma (the term for lava when the molten rock is still underground). Because of the temperatures difference between the magma and the pocket of gas, the crystals form slower, crystals which form slower tend to form in larger sizes and so with a geode, you have an outside which is made up of very fined grained crystals, too small to see and the inside, which is full of larger crystals. These samples are supplied in a white card tray with an information label, they are provided as a geode pair or as smaller geode fragments. These geodes would make a wonderful addition to any mineral collection.