In many cultures of the Old and New Worlds, this gemstone has been esteemed for thousands of years. The oldest evidence for this claim was found in Egypt, where grave furnishings with turquoise inlay were discovered, dating from approximately 3000 B.C.  Turquoise is a copper aluminum phosphate with a hardness of 6, i.e. considerably softer than quartz. In Nature, it occurs in the whole range of hues from sky blue to grey-green, and it is mostly found in places where there is a high concentration of copper in the soil. 

The blue colour is created by copper, the green by bivalent iron and a certain amount of chrome. Often, the material has veins or blotches running through it, which are brown, light grey or black depending on where it was found. These lively, more or less regular patterns are known as 'turquoise matrix'. The crystals are microscopically small and can hardly ever be recognized with the naked eye. As a rule, turquoise occurs as a filling in veins or crevices, or in the form of nuggets. The most well known deposits are in the USA, Mexico, Israel, Iran, Afghanistan and China. Some the most coveted turquoises, in a splendid light blue, come from deposits in the north of Iran.

I love turquoise with a lot of matrix with blue & green hues! Beautiful!!