Considered as one of the first gemstones that were mined, turquoise was already worked out by 4000 B.C. from the deposits in Sinai. A pure blue color is considered rare and most of the pieces have matrix which are, which can be of black, brown, or dark gray color. Turquoise comes in dense form, grape-like masses and as nodules and polishing makes the color more strong. As turquoise is porous, with aniline dyes and copper salts the color can be improved. Crushed or broken pieces of turquoise are reconstructed with paste, glass, ceramic and plastic. In 1972 Gilson in France produced a synthetic imitation of turquoise. Synthetic imitations are also known as neolite, hamburger turquoise and neo-turquoise.

Locations:

Sky blue turquoise comes from Iran whereas Tibet offers a greenish variety along-with Mexico and USA. Other locations where turquoise is found are Chile, the former USSR, Australia, and Cornwall (England).

Chemical Composition: Hydrated Copper Aluminum Phosphate
Crystal Structure: Triclinic
Hardness: 6
Specific Gravity: 2.80
Refractive Index: 1.61-1.65
Colors: Sky blue, bluish green and apple green.
Luster: Waxy to dull

Astrological Relevance:

Turquoise is considered to be one of the birthstones for the month of December, which covers two zodiac signs: Sagittarius (November 21 To December 21) and Capricorn (December 21 To January 21).