Geodes look like ordinary semi-spherical rocks on the outside but reveal beautiful crystals inside. They form when water flows hollow cavities in volcanic or sedimentary rock, depositing minerals that form crystals over millions of years. Inside them, there is a microcrystalline layer between the crystals and the outer rock layer called chalcedony. Chalcedony comes in different colors and patterns. Each one is unique, with varying shapes and colors of crystals inside depending on the mineral makeup deposited by groundwater. They are found all over the world but are most common in deserts or volcanic areas. Naturally colored geodes are not as intense as dyed ones and may not have as many exotic colors.
These contain agate, the most common form of chalcedony. They form in a wide variety of colors and striped patterns. When there is no hollow space, it is called a nodule instead of a geode.
They contain violet quartz crystals. The purple color comes from irradiation and the impurities of iron and other transition metals and trace elements. Uruguay, Siberia, Sri Lanka, and Brazil have the most high-quality ones.
These get their color from traces of titanium in the crystals.
They are most commonly white but can be found in various colors, including yellow, brown, orange, pink, red, purple, blue, green, gray, and black.
These, or Celestine Geodes, are typically a sky-blue color from the mineral strontium. However, they can range from yellow, orange, and greenish-grey.
The golden color of Citrine forms from Amethyst. The purple color of Amethyst turns yellow gold under high heat.
They come in many varieties and colors. Pure Quartz Geodes are transparent and translucent. Amethyst Geodes, Citrine Geodes, Rose Quartz Geodes, among others, are all familiar colored varieties of Quartz Geodes.
Rose Quartz Geode
these get their pale pink color from dumortierite. Usually, the rose quartz crystals are translucent instead of transparent.