Sapphire
Description
A transparent blue gemstone composed of corundum (aluminum oxide). Sapphires range in color from a pale blue to a deep indigo. They are mined in Myanmar (formerly Burma), Thailand, Kashmir, Sri Lanka, Australia (Victoria, Queensland, New South Wales), India, Madagascar, Russia, South Africa, and the U.S. (Montana, North Carolina). Sapphires are extremely hard and durable gemstones that have been used in jewelry since 1200 BCE. Oriented rutile crystal inclusions in a sapphire can produce a six-sided star effect called a Star Sapphire. Synthetic sapphires, produced commercially since 1902, are used in jewelry, watches, phonograph needles, instrument bearings, optical elements, and as abrasives.
Synonyms and Related Terms
corundum; alumina; aluminum oxide; star sapphire; safir (Dan.; Sven.); Saphir (Deut.); zafiro (Esp.); saphir (Fr.); saffier (Ned.); szafir (Pol.); safira (Port.);
Other Properties
Trigonal crystal system. Strongly pleochroic. Fracture = conchoidal or splintery
Insoluble in acids and alkalis. Luster = vitreous Streak = white
| Composition | Al2O3 |
|---|---|
| CAS | 1317-82-4 |
| Mohs Hardness | 9.0 |
| Melting Point | 2040 |
| Density | 3.96-4.05 |
| Refractive Index | 1.80 |
| Boiling Point | 1.76-1.78 |
Comparisons
Properties of Common Abrasives
Properties of Common Gemstones
Additional Images
Sapphire, cut and polished
Star sapphire
Sources Checked for Data in Record
- G.S.Brady, Materials Handbook, McGraw-Hill Book Co., New York, 1971 Comment: p. 693
- R.M.Organ, Design for Scientific Conservation of Antiquities, Smithsonian Institution, Washington DC, 1968
- Jack Odgen, Jewellery of the Ancient World, Rizzoli International Publications Inc., New York City, 1982
- R.F.Symmes, T.T.Harding, Paul Taylor, Rocks, Fossils and Gems, DK Publishing, Inc., New York City, 1997
- A.Lucas, J.R.Harris, Ancient Egyptian Materials and Industries, Edward Arnold Publishers Ltd., London, 4th edition, 1962 Comment: 1200-500 BC
- Encyclopedia Britannica, http://www.britannica.com Comment: "sapphire." Encyclopædia Britannica. 2005. Encyclopædia Britannica Premium Service. 15 Sept. 2005 .
- Wikipedia, the free encyclopedia, at http://www.wikipedia.com Comment: http://en.wikipedia.org/wiki/Sapphire (Accessed Sept. 14, 2005)
- Van Nostrand's Scientific Encyclopedia, Douglas M. Considine (ed.), Van Nostrand Reinhold, New York, 1976