Sapphire
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Sapphire | |
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![]() The 423-carat (85 g) blue Logan sapphire | |
General | |
Category | Oxide mineral |
Formula (repeatin unit) | aluminium oxide, Al2O3 |
Creestal seestem | Trigonal Seembol (32/m) Space Group: R3c |
Identification | |
Colour | Often Blue but varies |
Creestal habit | massive an granular |
Cleavage | none |
Fractur | conchoidal, splintery |
Mohs scale haurdness | 9.0 |
Skinkle | vitreous |
Streak | white |
Speceefic gravity | 3.95–4.03 |
Optical properties | Abbe nummer 72.2 |
Refractive index | nω=1.768–1.772 nε=1.760–1.763, Birefringence 0.008 |
Pleochroism | Strang |
Meltin pynt | 2030–2050 °C |
Fusibility | infusible |
Solubility | Insoluble |
Ither chairacteristics | coefficient o thermal expansion (5.0–6.6)×10−6/K |
Sapphire (Greek: σάπφειρος; sappheiros, 'blue stane',[1] which probably referred insteid at the time tae lapis lazuli) is a gemstane variety o the mineral corundum, an aluminium oxide (α-Al2O3). Trace amoonts o ither elements sic as airn, titanium, chromium, copper, or magnesium can gie corundum blue, yellae, purpie, orange, or a greenish colour. Chromium impurities in corundum yield a pink or reid tint, the latter bein cried a ruby.
References[eedit | eedit soorce]
- ↑ Harper, Douglas. "sapphire". Online Etymology Dictionary.