All About Turquoise

Turquoise Mines

A Stereo-graph of an old Turquoise Mine. If you cross your eyes right it can be seen in 3D (open source)

It is widely understood that different Turquoise mines produce different kinds of Turquoise. What is sometimes not considered is that within the bulk of any load of Turquoise from any one mine, there is a range in variety. Sometimes Turquoise is recognizable as being from a certain mine, but it can be easily misleading. The varieties, colors and characteristics from different mines overlap so it can be easy to mistake one type as another. By the time the Turquoise is carved, cut, polished and processed into the finished product the characteristics of a certain mine may become even less distinguishable, further confusing the types of Turquoise and their origin. A piece of Royston Turquoise from Nevada could be cut and polished to look like Sleeping Beauty for example. Rough Turquoise will always reveal more about its origins than cut material because the mother-stone, crystal structure, and fracture patterns all work together to communicate the Turquoise mine's personality. The differences in color and appearance come from chemical differences. And with geology, like baking, different amount of ingredients, ways of mixing, and different heats and cook times determine the properties you get. The chemical makeup of Turquoise allows for the blending of colors, swirls of color, and gradients. It also allows for the stretching of the definition of Turquoise. When you allow for the removal for some ingredients and the addition of others, properties change and variables increase. Different chemicals move in and are switched out for others depending on the geology and environment within which the Turquoise was formed. Replacing the copper with iron, for example, makes the Turquoise more green. In this section we attempt to give as much information about the various Turquoise mines as we can to give you the best chance at identifying a stone or selecting the type of Turquoise you desire.

Turquoise in the Southwest

Archeology

In North America, Turquoise mineral deposits are isolated to a limited geographical area in the southwestern states of Arizona, New Mexico, Nevada and Colorado. A small amount of Turquoise has been found in Mexico, and there are some deposits in western South America. Prehistoric Indians mined Turquoise from all of these locations and used it to produce jewelry by drilling beads and other hanging ornaments. There is evidence of prehistoric mining operations found in several areas, which include The Cerillos and Burro Mountain regions of New Mexico, the Kingman and Morenci regions of Arizona, and the Conejos area of Colorado. In southern Mexico and in excavated mounds east of the Mississippi, Turquoise jewelry has been analyzed and proclaimed to be from New Mexico's Cerillos mining area.

A selection of Ancestral Puebloan (Anasazi) Turquoise and orange argillite inlay pieces from Chaco Canyon (dated ca. 1020–1140 CE) show the typical color range and mottling of American Turquoise. (Courtesy Wikipedia.com)

Excavations at ancient Ancestral Pueblo sites like Chaco Canyon, Cliff Palace and Canyon de Chelly reveal the importance of Turquoise in the economy of the ancient southwest. The demand for precious materials created trade that extended to distant tribes in all corners of the continent. In some places like Chaco Canyon, evidence shows Turquoise was mined and exported along with Pipestone. In other areas shells including Spiny Oyster, were harvested and traded for Turquoise. The abundance of both materials found in excavations of ancient mounds reveals the existence of some type of economic system with Turquoise setting the standard of value as gold does today. Beaded necklaces and bracelets with Turquoise nuggets were a common way to display and carry one's Turquoise and wealth. They also carved fetishes and decorated clothing with beads, carvings and nuggets. Although it could be used as a form of currency, Turquoise also had deep spiritual meaning and even special power. The native people of the desert southwest believe Turquoise symbolizes a source of life-giving sun and precious renewing rain.

Turquoise & Coral

Kingman Turquoise and Coral Ring

The Native Americans of the southwest have a long tradition of pairing red-orange materials with Turquoise in their jewelry and art. The color contrast creates harmony and this reason alone is enough to explain the use of red orange shell, Coral, and stone alongside Turquoise. But the tradition is thousands of years old, rooted in symbolic meaning and regional materials. The original materials of the ancient American Indians would have been shell, jasper, fossilized coral, or pipestone. In recent years red Corals from the sea have become the standard because they are hard and easily polished. Early Native American ancestors had several choices for red-orange material even before the Spanish arrived. Shell, including the Spiny Oyster, was used often and traded from the coast to the interior. Red-orange stone like Argillites and pipestone would be more common for the interior Indians like those of Chaco canyon but are softer and wear down faster in jewelry. Fossilized red corals may also have been available in the pre-Colombian trade but would have been rare. Certain Coral living in the ocean today can have rich, red to orange hues and is very hard and easily polished. For this reason, it has become widely used in the American Indian jewelry of late regardless of its availability in ancient times. The red, white, and blue effect created when set next to Turquoise in Silver imparts a whole new meaning to the ancient color scheme.

A turquoise mine run that is the total content of turquoise containing ore produced in a period of time typically contains a wide range of turquoise ore which grades from inferior light “chalk” to the better grades of turquoise rough suitable for cutting into cabochons. The inferior chalk typically requires chemical stabilization for processing due to its insufficient hardness and/or color.

Stabilization methods typically involve the infusion of colored epoxy polymers into the stone under pressure. Many such processes have been developed over the years and this evolution has produced increasingly attractive stones for use in lower end jewelry. It is now sometimes very difficult to visually determine with certainty whether or not a given stone is natural or if it has been stabilized. Even the old tests such as the “hot needle test” or scratching the surface of a cab against a tooth are no longer definitiv.e In the end, one must depend on a “gut feel” as to whether or not a stone just seems to be a little bit too dull or too blue or that the matrix does not look natural to conclude that it is probably stabilized. The issue of stabilization is important as most high end turquoise consumers and quality jewelry makers strongly prefer natural turquoise to inferior turquoise which requires chemical treatment. This situation is analogous to the same dilemma with diamonds, emeralds, and rubies where natural stones command much higher prices.