Mineral Refractive Index Birefringence
no guarantee from various sources from various sources
     
Gadolinite 1.780 0.050
Gahnite 1.790 - 1.818 0.000
Gahnospinel 1.730 - 1.800 0.000
Gaspeite 1.610 - 1.810 0.220
Genthelvite 1.742 - 1.745 0.000
Goergeyite 1.560 - 1.570 0.024
Goshenite 1.566 - 1.602 0.004 - 0.008
Grandidierite 1.583 - 1.639 0.037
Grossular 1.730 - 1.760 0.000
Hackmanite 1.483 - 1.487 0.000
Hambergite 1.553 - 1.628 0.072 - 0.074
Hauyne 1.494 - 1.509  0.000
Heliodor 1.566 - 1.579 0.004 - 0.007
Hematite 2.880 - 3.220 0.280
Hemimorphite 1.614 - 1.636 0.021 - 0.022
Herderite 1.587 - 1.627 0.029 - 0.030
Hessonite 1.742 - 1.748 0.000
Hibonite 1.790 - 1.807 ?
Hiddenite 1.653 - 1.682 0.014 - 0.016
Hodgkinsonite 1.720 - 1.746 0.026
Hsianghualite 1.613 0.000
Huebnerite 2.170 - 2.320 0.120 - 0.130
Ilvaite 1.727 - 1.883 0.156
Imperial Topaz 1.605 - 1.640 0.008 - 0.016
Inderite 1.488 - 1.505 0.017
Inesite 1.609 - 1.644 0.035
Jadeite 1.640 - 1.667 0.012 - 0.020
Jasper 1.540 0.009
Jeremejevite 1.640 - 1.653 0.009 - 0.017
Johachidolite 1.712 - 1.726 0.008 - 0.014
Kornerupine 1.660 - 1.699 0.013 - 0.014
Kovdorskite 1.527 - 1.549 0.022
Kunzite 1.653 - 1.682 0.014 - 0.016
Kurnakovite 1.488 - 1.525 0.027 - 0.034
Kyanite 1.710 - 1.735 0.012 - 0.017
Labradorite 1.560 - 1.572  0.005 - 0.010
Lapis Lazuli 1.500 - 1.610 0.000
Larimar 1.595 - 1.645 0.028 - 0.038
Lawsonite 1.665 - 1.684 0.019 - 0.021
Lazulite 1.604 - 1.662 0.031 - 0.036
Lazurite 1.500 0.000
Lechatelierite 1.500 - 1.550 ?
Legrandite 1.675 - 1.740 0.038 - 0.060
Leifite 1.512 - 1.522 0.010 - 0.011
Lepidolite 1.525 - 1.587 0.029 - 0.038
Leucite 1.508 - 1.511 0.001