Querétaro: the Cradle of Opal Mining
In this region the opal deposits are located mainly in the mountain ranges of three municipalities: Columbus, Tequisquiapan and Ezequiel Montes. Most of the gems you see here are from the mines of La Trinidad in Tequisquiapan. During 1965 through 1975 the Queretaro opal mines were heavily over-mined and if you ask opal miners from back then, they will tell you it was much easier to find quality opals with alot of brilliant fire and play of color, where as today the gem quality opals are very hard to find, thus commanding hundreds to thousands of US dollars.
The oldest mine in Queretaro is Santa Maria del Iris - opened around 1870 and has been closed and reopened many times. At the moment there are about a 100 mines in the regions around Queretaro, but most of them have been closed for years. Originally the best quality of opals came from Santa Maria del Iris, followed by La Hacienda la Esperanza, Fuentezuelas, La Carbonera and La Trinidad. The important deposits in the state of Jalisco were not discovered until the late 1950's. In the year of 1957, Alfonso Ramirez (of Queretaro) accidentally discovered the first opal mine in Jalisco. The La Unica mine, located on the outer area of the "Volcan de Tequila", near the Huitzicilapan farm in Magdalena. By the early 1960's there were approximtely 500 known opal mines found in this region alone.
There are also less product and lower quality opal mines in Morelos, Durango, Chihuahua, Baja California, Guanajato, Puebla, Michoacan, and Estado de Mexico.