Ruby

A ruby is a pinkish red to blood-red colored gemstone, a variety of the mineral corundum. Ruby is one of the most popular traditional jewelry gems and is very... Wikipedia

• Category:  Oxide mineral variety
• Formula, (repeating unit):  aluminium oxide with chromium, Al 2O 3:Cr
• Crystal system:  Trigonal
• Crystal class:  Hexagonal scalenohedral (3m), H-M symbol: (3 2/m)
• Space group:  R 3c
• Colour:  Orangy red through strongly purplish red.
• Crystal habit:  Terminated tabular hexagonal prisms
• Cleavage:  No true cleavage
• Fracture:  Conchoidal, splintery
• Tenacity:  Brittle
• Mohs scale hardness:  9.0
• Luster:  Subadamantine, vitreous, pearly (on partings)
• Streak:  White
• Diaphaneity:  Transparent, translucent
• Specific gravity:  3.97–4.05
• Optical properties:  Uniaxial/−
• Refractive index:  n ω
• Birefringence:  0.008 to 0.010
• Pleochroism:  Strong: purplish-red – orangy-red
• Dispersion:  0.018
• Ultraviolet fluorescence:  Red under longwave
• Common impurities:  Cr. (sometimes:Ti, Fe)
• Data source:  DuckDuckGo