Mineralpedia Details for Corundum
Corundum
Likely named after the Sanskrit word for ruby, kurivinda, through the Tamil word kurundam. Hexagonal, prismatic, and sectorially striated crystals that can also occur in granular and massive forms. Corundum forms in a variety of colors including clear, gray, brown, pink to blood red, orange, yellow, green, blue to cornflower, and violet. Characteristically in Al-rich, Si-poor environments including in syenite and monzonite. It also occurs in high grade metamorphics and as detritus in placer deposits. It is found in numerous, worldwide localities.
c 2001-2005 Mineral Data Publishing
See also Handbook of Mineralogy, Anthony et al (1995) and MSA at http://www.handbookofmineralogy.org/pdfs/corundum.pdf
- Formula
- Al2O3
- Crystal System
- Trigonal
- Crystal Habit
- Euhedral Crystals, Tabular, Prismatic
- Cleavage
- None, None, None
- Luster
- Vitreous (Glassy)
- Color
- blue, red, yellow, brown, gray
- Streak
- none
- Class
- Trigonal - Hexagonal Scalenohedral
- Fracture
- Tough
- Hardness
- 9
- WebMineral
- View Corundum
- Mindat
- View Corundum
Corundum var. Sapphire from Passara, Uva Province, Sri Lanka
Sapphire crystal showing good striations and inclusions of a blue mineral. Overall 4 x 2 x 1.4cm.
Corundum var. Sapphire from Balangoda, Sabaragamuwa, Sri Lanka
Doubly terminated, yellow crystal, slightly water worn. Overall 6 x 2.5 x 2.5cm.
Corundum var. Ruby from Bajouri, Hassanabad, Hunza, Northern Areas, Pakistan
Prismatic deep red crystal with several nice faces to 2cm of Ruby Corundum.
Corundum var. Ruby from Jagdalik, Kabul Prov., Afghanistan
Well formed Ruby crystal to 1.8cm nicely exposed from white marble matrix.
Well formed Ruby crystal showing several good faces to 1cm.
Corundum var. Ruby from Fiskenaes, Nuuk, Kitaa Province, Greenland
Bright red, crude crystals of Ruby to 2mm throughout matrix.
Corundum from York River Skarn, Hastings Co., Ontario, Canada
A large blue-gray tapered Corundum crystal partially embedded in Biotite-Quartz matrix with one terminated end.
Corundum from Miass, Southern Urals, Russia
Rich blue large Corundum crystal showing twinning patterns and two crystal faces.
Corundum var. Ruby from Keivy Mountains, Kola Peninsula, Murmanskaja Oblast', Russia
Small ruby crystal to 8mm.
Corundum var. Ruby from Kola Peninsula, Russia
Thumbnail ruby with a single crystal to 1.5cm.
Corundum var. Ruby from Kleggasen Ruby quarry, Froland, Aust-Agder, Norway
Large ruby crystal to 3cm.
Corundum from Sterling Hill mine, Ogdensburg, Sussex Co., New Jersey, United States
A good representative specimen of altered country rock with red ruby crystals to 8mm, greenish Margarite and deep red Rutile.
Corundum from Mundarara mine, Longido, Mt. Kilimanjaro, Tanzania
Deep, bright red 2cm crystal grains in green Zoisite matrix.
Corundum from Zazafotsy quarry, Ihosy dist., Horombe, Fianarantsoa, Madagascar
A nice bluish purple prismatic sapphire Corundum crystal nicely exposed in biotite schist. The crystal is 3cm long and carries good luster but does not have color changing characteristics. There is a bit of a red zone at the center. Corundum is a good example of a high to medium-pressure metamorphism at high temperature. At this locality it occurs in metapelite, a metamorphosed fine-grained sedimentary rock.
Corundum from Bancroft, Ontario, Canada
Greyish blue large crystal of Corundum 3.5cm across. with a few smaller in granitic matrix.
Corundum from Ceylon, Sri Lanka
Blue twinned, excellent small crystal.
Corundum from Chester Emery mines, Hampden Co., Massachusetts, United States
Emery is Corundum mixed with Magnetite, thus the magic magnet.
