Cochise College          Photos of Minerals

                          Geology Home Page                

                          Roger Weller, geology instructor

                          wellerr@cochise.edu
                                  copyright 2007-R.Weller
 

Mineral Information on:
spinel


Chemical Group:   oxide

Chemical Formula: 
MgAl2O4

Color:  red, blue, green, yellow, brown, black, white, mauve                 Streak: white

 

Hardness:  8        Specific Gravity:  3.5 to 4.1

Luster: vitreous                  Fracture:  conchoidal

Tenacity:  brittle          Cleavage:  octahedral, imperfect
 

Fluorecence:  some spinels fluoresce

 

Crystal Forms:  Isometric system
     Usually occurs as an octahedron.
     Twins parallel to the octahedron face are known as spinel twins.

Mineral Associations:  corundum, magnetite, garnet, galena, diopside, vesuvianite,
     scapolite, sillimanite, cordierite, rutile, cassiterite, chalcopyrite, epidote, zircon

Rock Associations: basic rocks, pegmatites, dolomitic gneiss, placer deposits

Identifying Characteristics:

Uses:  gemstone

USA occurrences:
New York
     Amity
     Warwick
     Edenville
     Tilly Foster mine, Brewster
New Jersey
     Stirling Hill
     Limecrest Quarry, Franklin
     Ogdensburg, Sussex County
     Scrub Oak mine, Morris County
Massachusetts
     Cummington (gahnite-green spinel)
     Franklin County
North Carolina
     Culassaja mine, Franklin
     Galax, Alleghany County
Georgia
     Ball Ground, Cherokee County
Alabama
     Dudleyville, Tallapoosa County
New Mexico
     Mora, Santa Fe, Sandoval, Sierra, and McKinley counties
Texas
     Llano County
    
Oregon
WORLD-WIDE occurrences
Sri Lanka
Italy
     Vesuvius
Madagascar
Canada
     Ontario
     Prelude Lake near Yellowknife
Burma
Mexico
     Chihuahua
Malagasy
     Betroka
Afghanistan
     Balascia
Sweden
New Zealand
Brazil
Australia
     Anakie sapphire field of Quuensland
     Tasmania
     Beechworth, Australia

Additional Information:

The Black Prince's Ruby in the British Crown is actually a large red spinel.
Older names:
orange-red spinel: hyacinth spinel
yellow-orange spinel: rubicelle
dark green spinel: choro-spinel

black spinel: pleonaste
blue and violet spinel: ceylonite