Ruby
Variety of corundum
Very Rare · Al₂O₃
Red corundum coloured by chromium impurities. The most renowned rubies grew in marble during metamorphism; others come from amphibolites or were carried up by basalts. Star rubies display asterism caused by rutile needle inclusions oriented along the crystal axes.
Identity
- Formula
- Al₂O₃
- Chemical class
- Oxide
- Mineral group
- Corundum, Sapphire
- Also known as
- Red corundum, Carbuncle (archaic, any red gem)
- Used in alchemy
- Ruby Powder
Crystallography
- Crystal system
- Trigonal
- Habits
- Tabular, Prismatic, Rhombohedral
- Fracture
- Conchoidal
Physical properties
- Mohs hardness
- 9
- Density
- 4 g/cm³
- Luster
- Vitreous, Adamantine
- Colors
- red, pink-red, orange-red, garnet-red
- Streak
- white
- Transparency
- Transparent, Translucent
Geology
- Origins
- Metamorphic, Igneous
- Host rocks
- Volcanic rock, Schist and gneiss, Marble, River gravels and sands
- Associated minerals
- Spinel, Calcite, Mica, Rutile
- Found in
- Placer deposit
- Geography
- Myanmar, Sri Lanka, Thailand, Mozambique, Afghanistan
Classification
- Rarity
- Very Rare
- Gem quality
- Yes
Arcane properties
- Affinity
- Fire, Life
- Effects
- Elemental fire, Healing
- Planar origin
- Material Plane
Sources
- Ruby. Mindat.org (Hudson Institute of Mineralogy).
- Corundum. Mindat.org (Hudson Institute of Mineralogy).
- J. W. Anthony, R. A. Bideaux, K. W. Bladh, M. C. Nichols, Corundum. Mineral Data Publishing, Handbook of Mineralogy, 2001.
- Ruby. Gemdat.org (Hudson Institute of Mineralogy).
- Ruby Description. Gemological Institute of America, Gem Encyclopedia.
- Gaston Giuliani, Lee A. Groat, Geology of Corundum and Emerald Gem Deposits: A Review. Gemological Institute of America, Gems & Gemology, 2019.
- A Study of Rubies from Cambodia and Thailand. Gemological Institute of America, GIA News from Research.
- Garnet History and Lore. Gemological Institute of America, Gem Encyclopedia.
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