CHISOM IBEMERE
Turquoise is an Opaque, blue-greenish mineral and a hydrated phosphate of Copper and Aluminum. It is known with many names and it dated back 17th century. It’s name is derived from the French word ” turquois” which means “Turkish”. It was first known on the Sinai Peninsula of Egypt over 7500 years ago. It is rare and very valuable and prized for it’s equisite colour as an Ornamental stone.
Turquoise is soluble in hot hydrochloric acid when grounded. It has a refractive index of about 1.61-1.65. It is nearly cryptocrystalline and huge with no definite external shape. It may substitute some minerals pseudomorphously such as Feldspar, Apatite. It has same properties with chrysocolla but differs by it’s greater hardness.
Turquoise are one of the first mined gemstones with the highest mined in North America. It’s deposits are formed in different ways. It’s deposit occurs when hydrothermal fluids releases Copper from a rock. The leached Copper is redeposited in a more concentrated form as a Corper porphyry. This happens due to the conversion of existing feldspar to potassium feldspar and the deposition of Quartz and Micas at a temperature of 400-600oC.
Turquoise is widespread and comes in different sizes. They are useful in Jewelry and for Ornamental purposes which may include beads, Cabochons, Carvings and Inlays.
The value of Turquoise is based on its type which may be natural or reconstituted, colour and it’s size. The naturally formed ones are rare and more valuable. It is retailed between $1-$10 per carat.
Turquoise are mined in Nasarawa and in few other states in Nigeria.
