The Zuni believed that it protected them from demons. In Asia, turquoise was considered protection against the evil eye. Tibetans carved turquoise into ritual objects as well as wearing it in traditional jewelry. Turquoise was also thought to promote prosperity. Usually found in association with copper deposits, turquoise is sometimes collected as a by-product of copper mining.
Turquoise occurs as nodules and veins that are either blue or green in color.
The mineral is composed of hydrated copper and aluminum phosphate and is a secondary mineral deposited from circulating waters. It occurs chiefly in arid environments as blue to greenish, waxy veinlets in aluminum-rich, weathered, volcanic, or sedimentary rocks. The most important turquoise deposits are in Iran, Tibet, China, and the Southwestern United States. Turquoise from Iran is often said to be the best, because it is sometimes a clear sky blue with no green and no black veins running through the stones. Turquoise of equal quality is also produced in Arizona and New Mexico.