|
Beryl |
Corundum |
Diamond |
Quartz |
Chrysoberyl |
Spinel |
|
|
| Chem Comp. |
Al2Be3(Si6O18) |
Al2O3 |
C |
SiO2 |
Al2BeO4 |
MgAl2O4 |
|
| System |
Hexagonal |
Trigonal |
Cubic |
Trigonal |
Orthorhombic |
Cubic |
|
| Hardness |
7.5-8 |
9 |
10 |
7 |
8.5 |
8 |
|
| Cleavage |
Imperfect |
None |
Perfect |
None |
Imperfect |
Imperfect |
|
| Type/Cleave |
|
Octahedral |
|
| Fracture |
Concoidal |
Concoidal, splintery |
Concoidal, splintery, brittle |
Concoidal |
Conciodal, brittle |
Brittle, concoidal |
|
| Habit |
Long prism, rarely tabular |
tabular, short columnar, barrel
shaped |
Octahedron, dodecahedron, cube |
6 sided prism w/pyra termination,
interpentrant twinning, AGG: grainy, fibrous, columnar |
Thick
tabular, |
Octahedral, twinned |
|
| Localities |
S. Korea, India, Brazil, Sdakota,
WAustrail, New Hampshire US |
Burma, Thailand, Sri Lanka, |
S Africa, Russia, Namibia,
Austrail. CAN |
Germany, Alps, Brazil, Herkimer,
USA, CAN |
Sri Lanka, Burma, Urals, Brazil
,USA |
Sri Lanka, Burma, Thailand,
Orange County/NY/New Jersey, USA |
|
| GARNET
GROUP |
Chem Comp |
System |
Hardness |
Cleavage |
Fracture |
Habit |
Localities |
|
| Pyrope |
Mg3Al2(SiO4)3 |
Cubic |
6.5-7.5 |
Imperfect |
Concoidal, brittle, splintery |
Rhombdodecahedron,
icositetrahedron |
Safrica, US, Czecho, Saxony |
|
| Almandine |
Fe3Al2(SiO4)3 |
Cubic |
6.5-7.5 |
Imperfect |
Concoidal, brittle, splintery |
Rhombdodecahedron,
icositetrahedron |
Urals, Sri Lanka, India,
Scotland, Norway, NY |
|
| Spessartite |
Mn3Al2(SiO4)3 |
Cubic |
6.5-7.5 |
Imperfect |
Concoidal, brittle, splintery |
Rhombdodecahedron,
icositetrahedron |
Germany, Sweden, Madagascar, Sri
Lanka, Burma |
|
| Uvarovite |
Ca3Cr2(SiO4)3 |
Cubic |
6.5-7.5 |
Imperfect |
Concoidal, brittle, splintery |
Rhombdodecahedron,
icositetrahedron |
Finland, Urals,
Transvaal/Safrica, Brazil |
|
| Grossular |
Ca3Al2(SiO4)3 |
Cubic |
6.5-7.5 |
Imperfect |
Concoidal, brittle, splintery |
Rhombdodecahedron,
icositetrahedron |
Italy, Sri Lanka, Canada, Mexico,
US, Safrica |
|
| Andradite |
Ca3Fe2(SiO4)3 |
Cubic |
6.5-7.5 |
Imperfect |
Concoidal, brittle, splintery |
Rhombdodecahedron,
icositetrahedron |
Swiss, Austria |
|
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