Roger Weller, geology instructor
[email protected]
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