other names: Safir, corundum
mineral class: Oxides and hydroxides
chemical formula: Al2O3
Chemical elements: Aluminum, oxygen
Similar minerals: Kyanite, spinel, topaz, zircon
colour: blue, yellow, purple, green
shine: Glass gloss
crystal structure: trigonal
mass density: approx. 4.0
magnetism: not magnetic
Mohs hardness: 9
stroke color: White
transparency: transparent to opaque
General information about sapphire:
Of the sapphire describes a variety of corundum within the oxides, which is one of the world's hardest minerals with a Mohs hardness of 9 next to the diamond. Under the name sapphire are basically all blue varieties of corundum known, however, the coveted gemstone can appear in all other colors with the exception of red. Bright deep blue and dark blue specimens are particularly valuable, but also light blue, pale yellow, colorless, soft purple and greenish stones are processed into precious pieces of jewelry. The color provides important information about the location and is determined by the chemical admixtures of various minerals and elements. Iron and titanium are responsible for the coveted blue color, with low iron content of the stone is usually greenish or orange. The action of vanadium brings purple specimens to light.
The name derives not only from Latin and Greek, but also from old words that were used in Sanskrit, Hebrew and Old Iranian and can be translated as "love", "loved" or "Saturn". Like all stones, which are counted among the corundums, the sapphire is also a shell-like, brittle or splintered fracture and forms pyramidal, prismatic or barrel-shaped crystals as well as massive or granular aggregates. The gloss can be dull, glass or diamond-like, the transparency ranges from opaque to completely transparent.
Origin, occurrence and localities:
Like all corundum, sapphire is formed from rocks with a high aluminum and sodium concentration under high temperature and pressure conditions. It is promoted worldwide, with the major countries mostly associated with a single color variety. The cornflower blue sapphire is mainly produced in Indian Kashmir, while in Thailand green-blue varieties, in the US state of Montana light blue stones and in Sri Lanka violet, delicately purple, colorless and pink sapphires are widely used. Yellowish and dark blue to almost black specimens are found mainly in Australia.
History and usage:
As already mentioned, sapphire plays an economically important role, especially in the jewelry industry. The sharpening significantly increases the value of the stone, often resulting in prices that exceed those of diamonds. Primarily antique, drop-shaped or oval faceted stones from Sri Lanka and Kashmir are in great demand for the production of luxurious jewelery.
Since the 1950s, sapphires have also been made into scanned needles in turntables and used as components of scientific instruments in space research and various electrical precision equipment, as well as in lasers and LED lights. In the esoteric sapphire positive effects on the mental and physical health are attributed, which are not scientifically proven. Synthetically produced colorless sapphires are mainly used in watchmaking, since glass made of it reacts extremely insensitive to impacts and is characterized by a high light transmission.