Turquoise is a copper aluminum phosphate with a hardness of 5 to 6. Its striking blue color is caused by copper, while green shades are due to the addition of iron. From the French, pierre turquoise, meaning "Turkish stone," this opaque mineral may have the longest historical use of all gemstones—beads dating back 5000 years have been found in Iraq. Turquoise has long been used for jewelry and as decorations for objects such as weapons and amulets. Early Native Americans began mining turquoise and it has been found in the burial sites of numerous tribes. Turquoise teaches the wisdom of compassion and forgiveness, and can give the wearer a sense of serenity and peace. Most turquoise is mined in Iran, China and the southwestern United States.