Geologic Landscapes & Observations of Surrounding Nature: New Mexico’s State Gem – Turquoise

The state of New Mexico has recognized a state fossil and a state gem. The state gem of New Mexico is, not surprisingly, turquoise.

Chemically, that gem is a phosphate of aluminum carrying small quantities of copper and iron and a green mineral, variscite. These give the gemstone its color as well as its value and beauty. This is the only phosphate that is considered a precious stone. Turquoise is typically formed by alteration of igneous rocks rich in copper.

Turquoise has been mined in New Mexico for thousands of years, playing a significant role in Native American culture. The Cerrillos mining area near Santa Fe is among North America’s oldest sites, and turquoise from this region became a valuable trade item mined by Pueblo peoples with basic tools. The other three main areas for turquoise in New Mexico are the Burro Mountains district in the vicinity of Tyrone in Grant County; the Eureka (Hachita) district, also in Grant County; and the Orogrande (Jarilla) district, in Otero County (“Turquoise in New Mexico,” 1979, by Robert H. Weber New Mexico Geology, v. 1, n. 3 pp. 39-40).

Turquoise set in silver by numerous silversmiths is a big industry in New Mexico and beautiful and authentic pieces may be purchased on reservations or at fashionable stores throughout the United States.

Turquoise is about the same hardness as window glass but is porous. According to the Gemological Institute of America, typically, turquoise is judged on three basic qualities — its color, its texture and the presence or absence of matrix. Turquoise ranges from blue to green. Generally, pure saturated blue shades are the most valuable.

Some collectors prefer the look of turquoise with spiderweb patterns of matrix. Lower-quality turquoise is softer and more porous and is often treated to make it durable enough to wear. The natural mineral may be modified (stabilized) to harden the stone by using epoxy or acrylic to fill the material’s pores; color-enhanced turquoise has undergone the same process as stabilized turquoise, but dye has been included to enhance the color of the stone. Reconstituted turquoise is made from chalky turquoise that is ground into powder and mixed with dyes and epoxy, then molded into a solid form.

When taking care of turquoise jewelry, note that natural turquoise can absorb things like cleaning products, perfume or metal polish, which may affect its color.

The Turquoise museum in downtown Albuquerque has multiple displays of this gem, and the free Mineral Museum in Socorro has a special section with turquoise from each area in the state.