Refractive Index (low) between
Specific Gravity (low) between
Birefringence
Optical Character
No data was found
Gadolinite
2 positive, iso
RI MIN
1.770
RI MAX
1.820
DI MIN
4.00
DI MAX
4.65
BF MIN
0.010
BF MAX
0.040
Hematite
1 negative
RI MIN
2.870
RI MAX
3.220
DI MIN
4.95
DI MAX
5.28
BF MIN
0.280
BF MAX
0.280
Cinnabar
1 positive
RI MIN
2.905
RI MAX
3.256
DI MIN
8.09
DI MAX
8.10
BF MIN
0.351
BF MAX
0.351
Pyrargyrite
1 negative
RI MIN
2.880
RI MAX
3.080
DI MIN
5.82
DI MAX
5.85
BF MIN
0.200
BF MAX
0.200
Opal
iso, aggr
RI MIN
1.370
RI MAX
1.475
DI MIN
1.95
DI MAX
2.25
BF MIN
BF MAX
Cryolite
2 positive
RI MIN
1.338
RI MAX
1.340
DI MIN
2.95
DI MAX
2.97
BF MIN
0.001
BF MAX
0.001
Villiaumite
iso
RI MIN
1.326
RI MAX
1.332
DI MIN
2.78
DI MAX
2.81
BF MIN
BF MAX
Corundum - "Sapphire"
1 negative
RI MIN
1.757
RI MAX
1.779
DI MIN
3.97
DI MAX
4.10
BF MIN
0.008
BF MAX
0.009
Benitoite
1 positive
RI MIN
1.756
RI MAX
1.805
DI MIN
3.61
DI MAX
3.80
BF MIN
0.043
BF MAX
0.047
Baryte
2 positive
RI MIN
1.632
RI MAX
1.650
DI MIN
4.30
DI MAX
4.60
BF MIN
0.010
BF MAX
0.018