Mindat Logo
Home Page Log In Message Board The Mindat Directory
Register Search Pages Chat Now! (2 online) Mindat Auctions

Corundum

Big Photo

United Jack Mine, Zoutpansberg District, Murchison Range, Limpopo Province, South Africa
© Rob Lavinsky

Show Corundum Photos (245)
Formula:
Al
 
2
O
 
3
System:TrigonalColour:Colourless, blue, red, ...
Hardness:9
Name:Derived from the Sanskrit, kuruvinda ("Ruby")


Hematite Group.
The aluminum analogue of Eskolaite, Hematite, and Karelianite.
The red (Cr-bearing) gem variety is called Ruby.

Classification of Corundum

IMA status:Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
Strunz 8th edition ID:4/C.04-10
Nickel-Strunz 10th (pending) edition ID:4.CB.05

4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
C : Metal: Oxygen = 2: 3,3: 5, and similar
B : With medium-sized cations
Dana 7th edition ID:4.3.1.1
Dana 8th edition ID:4.3.1.1

4 : SIMPLE OXIDES
3 : A2X3
Hey's CIM Ref.:7.6.1

7 : Oxides and Hydroxides
6 : Oxides of Al
mindat.org URL:http://www.mindat.org/min-1136.html
Please feel free to link to this page.

Occurrences of Corundum

Geological Setting:Silica-poor rocks, such as Nepheline-Syenites, alkali igneous undersaturated rocks, contact aureoles in altered aluminous shales, aluminous xenoliths in high temperature plutonic and hypabyssal rocks, metamorphosed bauxite deposits, and as a detrital material in sediments.

Physical Properties of Corundum

Lustre:Adamantine, Vitreous, Pearly
Diaphaneity (Transparency):Transparent, Translucent, Opaque
Colour:Colourless, blue, red, pink, yellow, grey, golden-brown
Streak:White
Hardness (Mohs):9
Hardness Data:Mohs hardness reference species
Tenacity:Brittle
Cleavage:None Observed
Parting:Rhombohedral and basal parting {0001}, sometimes perfect but interrupted; also on {1011} due to exsolution (Boehmite), observed on large blocks (Georgia, USA).
Fracture:Irregular/Uneven, Conchoidal
Density (measured):3.98 - 4.1 g/cm3
Density (calculated):3.997 g/cm3

Crystallography of Corundum

Crystal System:Trigonal
Class (H-M):3m (3 2/m) - Hexagonal Scalenohedral
Space Group:R3c {R3 2/c}
Cell Parameters:a = 4.75Å, c = 12.982Å
Ratio:a:c = 1 : 2.733
Unit Cell Volume:V 253.54 ų
Z:6
Morphology:Often steep pyramidal on w, z, E, or ω. Barrel-shaped crystals that are often rough and rounded, of considerable size at times, varying from short prismatic [0001] with a large base to steep pyramidal. Less commonly, flat tabular {0001} or rhombohedral. Striae on {0001} parallel [011¯0]. Lines in the direction [112¯0] divide the base into six sectors at times.
Twinning:1. Common {1011}; usually lamellar, producing a lamellar structure and striae on c and r. Less commonly penetration twins or arrowhead twins with crystals tabular {1120}. 2. On {0001}, less common. Pressure twinning produced on {1011}, and on {0001}.
Crystal Atlas:
Image Loading
Click on an icon to view
Corundum no.17 - Goldschmidt (1913-1926)
Corundum no.34 - Goldschmidt (1913-1926)

About Crystal Atlas

You may need to scroll this box using your mouse to view the full instructions.

The mindat.org Crystal Atlas allows you to view a selection of crystal drawings of real and idealised crystal forms for this mineral and, in certain cases, 3d rotating crystal objects. You need Java to see these. You can download Java for free - click here to download Java

The 3d models and java code are kindly provided by www.smorf.nl. You can control the movement of the models by holding down the left mouse-button over the 3d model and moving your mouse. Keyboard controls are:

: default positions
t/T: decrease/increase transparency x/X: next/previous texture
b/B: next/previous background w: toggle wireframe
s: toggle sticks m: toggle miller indices
k: toggle crystallographic axes =/-: zoom in/out
r: stop/start rotation 1/2/3
Structure
  Reference
Pauling L Hendricks S B (1925) Crystal structures of hematite and corundum Locality: Ceylon. Journal of the American Chemical Society 47:781-790.

Show
Unit Cell | Structure | Polyhedra

Style
Black Background | White Background

Rotation
Stop | Start

Labels
Label Atoms | Off

More Crystal Structures
Click here to view more crystal structures at the American Mineralogist Crystal Structure Database
X-Ray Powder Diffraction:
Image Loading

Radiation - Copper Kα
Data Set:
Horizontal Axis: ° to ° Vertical Axis: % Source Data: Filtered Data: Peaks:
Data courtesy of RRUFF project at University of Arizona, used with permission.

Optical Data of Corundum

Type:Uniaxial (-)
RI values: nω = 1.767 - 1.772 nε = 1.759 - 1.763
2V:Measured: 58°
Birefringence:Low, first-order greys and whites.
Maximum Birefringence:δ = 0.008 - 0.009

Chart shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:High
Colour in reflected light:Colourless
Pleochroism:Not Visible
Comments:Weak in sapphire (e = blue-green to yellow-green, o = pale to deep blue), otherwise none visible.
Comments:Asterism often present due to oriented needle-like inclusions or to colloidal or other material deposited in oriented tubules.

Chemical Properties of Corundum

Formula:
Al
 
2
O
 
3
Essential elements:Al, O
All elements listed in formula:Al, O
Analytical Data:
Al(52.93)
O(47.07)
Empirical Formula:
Al
 
2
O
 
3
Common Impurities:Cr,Fe,V,Ti

Relationship of Corundum to other Species

Member of Group:
Hematite Group:
M
 
2
O
 
3
Related Minerals - Nickel-Strunz Grouping):

- +
4.CB.05Brizziite
NaSb
5+
 
O
 
3
4.CB.05Ecandrewsite
(Zn,Fe
2+
 
,Mn
2+
 
)TiO
 
3
4.CB.05Eskolaite
Cr
 
2
O
 
3
4.CB.05Geikielite
MgTiO
 
3
4.CB.05Hematite
Fe
 
2
O
 
3
4.CB.05Ilmenite
Fe
2+
 
TiO
 
3
4.CB.05Karelianite
V
 
2
O
 
3
4.CB.05Melanostibite
Mn
2+
 
(Sb
5+
 
,Fe
3+
 
)O
 
3
4.CB.05Pyrophanite
Mn
2+
 
TiO
 
3
4.CB.05Akimotoite
(Mg,Fe
2+
 
)SiO
 
3
4.CB.05Auroantimonate
AuSbO
 
3
4.CB.05Romanite
([],Pb,Ca)UFe
2+
2
(Ti,Fe
3+
 
)
 
6
Ti
 
12
O
 
38
4.CB.05UM1998-11-O-AuHSb
Au
 
2
SbO
 
2
(OH)
4.CB.05Tistarite
Ti
 
2
O
 
3
4.CB.10Avicennite
Tl
 
2
O
 
3
4.CB.10Bixbyite
(Mn
3+
 
,Fe
3+
 
)
 
2
O
 
3
4.CB.15Armalcolite
(Mg,Fe
2+
 
)Ti
 
2
O
 
5
4.CB.15Pseudobrookite
Fe
 
2
TiO
 
5
4.CB.15Mongshanite
(Mg,Cr,Fe
2+
 
)
 
2
(Ti,Zr)
 
5
O
 
12
4.CB.20Zincohögbomite-2N2S
(Zn,Al,Fe)
 
2
(Al,Fe,Ti)
 
8
O
 
15
(OH)
4.CB.20Zincohögbomite-2N6S
(Zn,Al)
 
7
(Al,Fe,Ti,Mg)
 
16
O
 
31
(OH)
4.CB.20Magnesiohögbomite-6N6S
(Mg,Al,Fe)
 
2
(Al,Ti)
 
8
O
 
15
(OH)
4.CB.20Magnesiohögbomite-2N3S
(Mg,Fe,Zn,Ti)
 
3
(Al,Fe)
 
10
O
 
19
(OH)
4.CB.20Magnesiohögbomite-2N2S
(Mg,Al,Fe)
 
2
(Al,Fe,Ti)
 
8
O
 
15
(OH)
4.CB.20Ferrohögbomite-6N12S
(Fe,Mg,Zn)
 
4
(Al,Ti,Fe)
 
12
O
 
23
(OH)
4.CB.25Pseudorutile
Fe
 
2
Ti
 
3
O
 
9
4.CB.30Berdesinskiite
V
3+
2
TiO
 
5
4.CB.30Oxyvanite
V
 
3
O
 
5
4.CB.35Olkhonskite
(Cr,V)
 
2
Ti
 
3
O
 
9
4.CB.35Schreyerite
V
 
2
Ti
 
3
O
 
9
4.CB.40Kamiokite
Fe
 
2
Mo
 
3
O
 
8
4.CB.40Nolanite
(V,Fe,Fe,Ti)
 
10
O
 
14
(OH)
 
2
4.CB.40Rinmanite
Zn
 
2
Sb
 
2
Mg
 
2
Fe
 
4
O
 
14
(OH)
 
2
4.CB.45Claudetite
As
 
2
O
 
3
4.CB.45Stibioclaudetite
AsSbO
 
3
4.CB.50Arsenolite
As
 
2
O
 
3
4.CB.50Sénarmontite
Sb
 
2
O
 
3
4.CB.55Valentinite
Sb
 
2
O
 
3
4.CB.60Bismite
Bi
 
2
O
 
3
4.CB.65Sphaerobismoite
Bi
 
2
O
 
3
4.CB.70Sillénite
Bi
 
12
SiO
 
20
4.CB.75Kyzylkumite
V
 
2
Ti
 
3
O
 
9
4.CB.80Tietaiyangite
Fe
3+
4
Fe
2+
 
TiO
 
9
Related Minerals - Hey's Index Grouping:

- +
7.6.2Böhmite
AlO(OH)
7.6.2Diaspore
AlO(OH)
7.6.4Gibbsite
Al(OH)
 
3
7.6.5Bayerite
Al(OH)
 
3
7.6.6Nordstrandite
Al(OH)
 
3
7.6.7Doyleite
Al(OH)
 
3
7.6.8Akdalaite
4Al
 
2
O
 
3
 · H
 
2
O
Related Minerals - Dana Grouping):

- +
4.3.1.2Hematite
Fe
 
2
O
 
3

Other Names for Corundum

Synonyms:
α-Aluminaa-Corundumα-CorundumAluminaAyatite
CorinendumCorinindumCorivendumCorivindumCorrindon
CorunditeCorundum-αCorundum-alphaCorundumiteHarmophane
KarundKorunduviteSoimontiteSpath AdamantinWhite Sapphire
Zircolite
Other Languages:
French:Corindon
Corindon adamantin
Corindon harmophane
German:Ajatit
Ayatit
Corundit
Corundumit
Demantspath
Korund
Korunduvit
Soimontit
Zircolith
Italian:Corindone
Latin:Adamas siderites
Russian:Корунд
Spanish:Ayatita
Corundita
Corundumita
Korunduvita
Soimontita
Zircolita
Varieties:
Adamantine SparAlundumAsteriated SapphireBarklyiteBlue Alexandrite
ChlorosapphirChromian CorundumLedo frozen fireOriental AmethystOriental Emerald
Oriental TopazPadmaragayaRubySapphireStar Corundum
Star RubyStar Sapphire

Other Information

Health Warning:None.
Industrial Uses:Corundum is used as an abrasive ("Emery"), and the gem varieties of corundum are better-known as Ruby and Sapphire.

References for Corundum

Reference List:Haüy (1805), Ann. Phys.: 20: 187.

Lucas (1806): 1: 257.

Judd (1895), Mineralogical Magazine: 11: 49.

Goldschmidt and Schroeder (1910), Min. Mitt.: 29: 461.

Spencer (1927) Mineralogical Magazine: 21: 329.

Palache, Charles, Harry Berman & Clifford Frondel (1944), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana Yale University 1837-1892, Volume I: Elements, Sulfides, Sulfosalts, Oxides. John Wiley and Sons, Inc., New York. 7th edition, revised and enlarged: 520-527.

Anastasiou, P. and Seifert, F. (1972) Solid solubility of Al2O3 in enstatite at high teperatures and 1-5 kb water pressure. Contributions to Mineralogy and Petrology: 34: 272-287.

Arima, M. and Onuma, K. (1977) The solubility of alumina in enstatite and the phase equilibria in the join MgSiO3-MgAl2SiO6 at 10-25 kbar. Contributions to Mineralogy and Petrology: 61: 251-265.

Franzini M., Troysi M., Cecchini A.(1986): La microdurezza del corindone. Atti Soc. Sc. Nat. Mem. Serie A, 93, 87-100.

Zeitschrift für Kristallographie: 117: 233-237.

Sutherland, F.L., Hoskin, P.W.O., Fanning, C.M., and Coenraads, R.R. (1998) Models of corundum origin from alkali basaltic terrains: a reappraisal. Contributions to Mineralogy and Petrology: 133: 356-372.

Articles/Blogs about Corundum

Article entries:
Corundum Crystals from the San Jacinto Mountains by K. L. Gochenour 2000Scott L. Ritchie

Internet Links for Corundum

Search Engines:
  • Look for Corundum on Google
  • Look for Corundum images on Google
    • External Links:
  • Look for Corundum on Webmineral
  • Look for Corundum on Athena Mineralogy
  • Look for Corundum on Wikipedia
  • Look for Corundum on Mineralien Atlas
  • Raman and XRD data at RRUFF project
  • American Mineralogist Crystal Structure Database
  • Search for Corundum in the Natural History Museum (London) online catalogue
  • Corundum details from Handbook of Mineralogy (PDF)
    • Mineral Dealers:
  • The Arkenstone - Fine Minerals
  • Buy fine minerals and gemstones from Pala International
  • rare and unusual minerals mainly crystallized
  • Top quality minerals from Kristalle of California
  • Rare and Unusual minerals at Mineralogical Research Company
  • Edwards Minerals - Fine Specimens
  • Fine Minerals from Dan Weinrich Minerals
  • Lapis Mineral Magazin
  • High-end worldwide specimens & outstanding customer service
  • Find Corundum on www.crystalclassics.co.uk
  • Search for - Corundum - on e-Rocks Mineral Sales & Auctions
  • Buy Minerals and Crystals from Crystalarium.com
    • Jobs:
  • Mining & Geology Jobs

    • Page Sponsor

    Sponsorship:This page is currently not sponsored. Click here to sponsor this page.

    Localities for Corundum

    Show Locality List (842 Items)
    The map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.
    Mineral and/or Locality
    Google
     
    www.mindat.org Web
    Copyright © Jolyon Ralph and Ida Chau 1993-2009. Site Map. Locality, mineral & photograph data are the copyright of the individuals who submitted them.Further information contact the Site hosted & developed by Jolyon Ralph. Mindat.org is an online information resource dedicated to providing free mineralogical information to all. Mindat relies on the contributions of hundreds of members and supporters. If you would like to add information to improve the quality of our database, then click here to register. Current server date and time: 28th Oct 2009 07:05:27