Turkus

Turkus, commonly called turquoise in English, refers to both a mineral and the blue-green color associated with it. The mineral turquoise is a hydrated copper aluminum phosphate with formula CuAl6(PO4)4(OH)8·4H2O, typically opaque to translucent, with a waxy to vitreous luster. The color turquoise ranges from sky blue to greenish blue; its hue is influenced by copper content and impurities, and it often appears with natural matrix patterns.

The term turquoise derives from the French pierre turquoise, which borrowed from Turkish turkuaz, meaning "Turkish stone," a reference to trade routes through the Ottoman Empire.

Turquoise forms in arid regions where copper-bearing rock interacts with aluminous phyllosilicates; major sources include Iran, the southwestern United States (especially Arizona and Nevada), Egypt, China, and Mexico. It has been used for thousands of years in jewelry and ornamentation, valued both for its vivid color and as an amulet in several cultures, notably ancient Egypt and Native American traditions.

Care and treatment: Natural turquoise is relatively soft (Mohs hardness 5–6) and often porous; many specimens are stabilized with resins to enhance durability. Untreated stones require gentle cleaning and protection from oils and solvents.

In modern design, turquoise remains popular as a complement to blues and earth tones. In digital color systems, turquoise commonly corresponds to the hex value #40E0D0.