By Julie Etra

Yes, Mexico mines and refines opals, primarily around Querétaro today and formerly in the state of Jalisco. Opal enthusiasts can even take tours near La Trinidad, less than 30 minutes from Tequisquiapan, to explore the region’s rich opal deposits (see Kary Vannice’s article elsewhere in this issue).

Global Distribution
Opals are found worldwide in specific geological formations, with each region producing distinct varieties. In addition to Mexico, opal mines exist in Germany, France, Spain, New Zealand, Australia, England, and Nevada, USA. Nevada opal, found in the Virgin Valley northeast of Las Vegas, is a type of fire opal, similar to the vibrant opals mined in Mexico.

The Origins of the Name
The word “opal” is derived from the Latin opalus, related to sight and light, while the Greek opallious means “to see a change of color.” Opals have been admired since ancient times, with the Roman author and naturalist Pliny the Elder describing them around 55 A.D.

In the Aztec civilization, opals were known as Vitzitziltecpa in the Nahuatl language, meaning “hummingbird stone.” The Aztecs believed opals had magical and healing properties, and these gemstones, mined in Querétaro, were often presented as tribute to the rulers of Tenochtitlán. Examples of these opals can be seen today at the Museo del Templo Mayor in Mexico City.

Legends and Myths
One of the most famous legends about opals comes from India. In Hindu mythology, the gods Brahma, Shiva, and Vishnu quarreled over a beautiful maiden. The Eternal One, tired of their bickering, transformed her into a cloud and dyed it in multiple colors to distinguish it from others. As the cloud dissolved into rain and touched the earth, it created opal—known as the “stone of a thousand colors.”

Types of Opals
Opals are classified into two main types: precious (also called noble) and common. The key difference is that precious opals exhibit a “play of color,” shifting hues depending on the angle and light, while common opals are typically translucent and lack this effect.

Precious Opal Varieties:
Black Opal: A dark-bodied opal (black, dark blue, or gray) with striking play of color.

White Opal: Light-colored (white or pale cream) with a delicate color play.

Boulder Opal: Found attached to its ironstone or sandstone host rock.

Crystal Opal: Transparent to semi-translucent with vibrant play of color.

Matrix Opal: Displays color play throughout the entire stone, not just on the surface.

Fire Opal: Translucent to transparent with red, orange, or yellow hues, often found in Mexico.

Pink Opal: A common opal variety ranging in shades of pink.

Hyalite Opal: A clear, glass-like opal with no play of color.

Dark Opal: Has a darker body tone but is not as deep as black opal.

Common Opal (also known as Potch):
– Lacks the characteristic play-of-color found in precious opal.
-Can be found in various colors, including purple, pink, blue, and green.

·Doublet and Triplet Opals:
These are assembled opals, where a thin layer of opal is bonded to a backing (doublet) or sandwiched between two pieces of resin or potch (triplet).

Opal Formation
Opals are formed through volcanic activity and are composed of a silica-based gel that can contain up to 10% water. Silica, a compound of silicon and oxygen, is also found in quartz crystals and beach sand.

Opal formation is associated with geothermal activity—hot springs and geysers bring silica-rich water to the surface, where it settles into cracks and fissures, gradually hardening into layers. Opals most commonly form in rocks such as:

Limonite: An iron ore.
Sandstone: A sedimentary rock.
Marl: A light-colored, carbonate-rich mud found in freshwater and marine environments.
Rhyolite & Basalt: Volcanic rocks associated with Mexico’s opal deposits.

Mexican Opals
Mexico is famous for its fire opals, which range from translucent to transparent red, orange, and yellow. Despite their name, not all fire opals exhibit play of color—the term refers to their body color rather than optical effects.

Opals were prized by the Aztecs, but large-scale mining did not resume until the early 1800s, when Querétaro became a major hub for opal extraction. In the 1950s, opals were discovered northwest of Guadalajara in Jalisco, near the town of Magdalena. By the 1960s, Magdalena was surrounded by hundreds of small-scale mines. Although much of the area was mined out by the 1970s, some open-pit mining continues today, using bulldozers and backhoes to extract opals from rhyolite formations.

If you’re looking to purchase fire opals, La Crucecita offers various options—but quality varies. For expert guidance and high-quality stones, Cielito Lindo is a trusted local jeweler.