Amethysts are the most valuable variety of quartz, and were one of the first gemstones used by people around the world. The Greeks believed that drinking wine from an amethyst cup would prevent intoxication. Royalty has also favored the purple gemstone, and at one time amethysts were reserved for royalty alone. The rich purple color is due to iron and manganese inclusions. Exposure to heat or irradiation can produce a yellow to orange color (citrine) or a pale green color (prasiolite). The hexagonal crystal structure can vary in size from microcrystalline drusy to large scepters and often forms inside agate geodes. South Brazil is rich in minerals found in its mountainous basalt rock formations.

Eons ago, as 2400 degree Fahrenheit magma cooled, pockets of gas became trapped in the magma. The pockets of gas later became hollow cavities in the solid, newly formed basalt rock. These hollow cavities became filled with super-hot mineral-laden ground water which resulted in layers of agate and quartz crystals forming inside. Miners in Brazil use hand tools to extract agate geodes from eroded mountain sides. For generations Brazilian miners have learned to cut the geodes in half, polish the cut surface, sides and some of the backs. The miners sell the worked geodes to collectors who enjoy their beauty and wonder.

This Amethyst Cathedral Geode is 10.5 inches long, 13 inches thick, and 19 inches tall. Due to the size and weight of the Amethyst, it is Pickup Only from the Houston Museum of Natural Science. We can offer Local Delivery to the Greater Houston Area.