Dugway Geode
Utah (USA) - The most common mineral found within them is quartz in various crystals clear, amethyst, and pink.
Septarian Geode
Utah (USA) - Is a combination of yellow calcite, brown aragonite, grey limestone and white/clear barite.
Las Choyas Geode
Chihuahua (Mexico) - The most common mineral found within them is quartz in various crystals clear, smokey, and if you are lucky amethyst.