#725 Mexican Opal Freeform
1/2" across. This opal was born in fire, in the ancient volcanoes of Mexico. Fire opal forms when water seeps into silica-rich lava, filling seams and hollows. Under heat and pressure, the silica forms a solid gel, trapping the remaining water within its structure. Small pebbles of fire opal are found embedded in lava flows.The vast majority is from Mexico. Mexican opal is mined in the Mexican states of Queretaro, Hidalgo, Guerrero, Michoacan, Julisio, Chihuahua and San Luis Potosi. The most important mines in Queretaro were discovered in 1835 and are still producing today.