Turquois is a secondary mineral, often associated with limonite, quartz, feldspar or kaolin. It occurs in veins, stalactic masses and as coatings or crusts, and grains or rounded pebbles. It has a hardness of 6, SG of 2.6 to 2.8, and is various shades of blue and green. It is used as a gem mineral. The specimen in the photo is from a vein of turquois found in New Mexico. The color of turquois will fade with time. Vein turquois generally occurs in thin laminate sections, similar to those in the photo of turquois ore. It is very popular with the American Indians, and peoples of the southwest and western US.