Opal is a hydrated silica with a hardness of 5.5 to 6.5. It comes in a variety of forms, one of the most popular today being “boulder opal,” which forms in an ironstone matrix. Opal forms when silica-rich water fills the cracks and voids of rocks, clay, and fossils. Though opal has been the subject of historical misconception and superstition, it has an even longer history of being both exalted and coveted for its beauty. It was the ancient Romans who provided the first real market for opals, raising the opal to gemstone status around 100 B.C. Today, opal is said to encourage optimism, confidence, playfulness and curiosity. While it can be found in many different locations such as the US, Mexico, Ethiopia, Brazil, Guatemala, and Japan, it is primarily found in Australia.
Fire opal, also known as Mexican opal, is a transparent to semi-transparent variety of opal, often without its signature opalescence. Its color ranges from reddish orange to orange yellow. The best known source for fire opal is Hidalgo, Mexico, where it is found in volcanic rock deposits that have been mined since the 14th century. Fire opal is believed to help overcome shyness, awaken passion, ease inhibitions, and promote artistic creativity. As a main variety of opal, it is also considered the birthstone for October.