Turquoise

n. opaque semi-precious stone of greenish-blue or sky-blue color used in jewelry; greenish-blue color

adj. having a greenish-blue color; having the characteristics of or being made of turquoise

Turquoise is an opaque, blue-to-green mineral that is a hydrous phosphate of copper and aluminium, with the chemical formula CuAl6(PO4)4(OH)8·4H2O. It is rare and valuable in finer grades and has been prized as a gem and ornamental stone for thousands of years owing to its unique hue. In recent times turquoise, like most other opaque gems, has been devalued by the introduction of treatments, imitations, and synthetics onto the market, some difficult to detect even by experts.
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Noun
1. a blue to gray green mineral consisting of copper aluminum phosphate; blue turquoise is valued as a gemstone
(hypernym) mineral
2. a shade of blue tinged with green
(synonym) greenish blue, aqua, aquamarine, cobalt blue, peacock blue
(hypernym) blue, blueness

adj. turquoise, greenish-blue color

n. turquoise, opaque semi-precious stone of greenish-blue or sky-blue color used in jewelry; greenish-blue color

(n.)
Alt. of Turquois
  

(a.)
Having a fine light blue color, like that of choice mineral turquoise.