Sapphire

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Sapphire
Logan Sapphire SI.jpg
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 instead 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.

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