Mineral	Refractive Index	Birefringence
no guarantee	from various sources	from various sources
Quartz	1.543 - 1.554	0.009
Red Beryl	1.561 - 1.598	0.004 - 0.007
Remondite-(Ce)	1.632 - 1.638	0.006
Rhodizite	1.690	0.000
Rhodochrosite	1.578 - 1.840	0.218 - 0.220
Rhodolite	1.745 - 1.760	0.000
Rhodonite	1.711 - 1.752	0.011 - 0.014
Richterite	1.615 - 1.636	0.021
Ruby	1.757 - 1.779	0.008
Rutile	2.616 - 2.903	0.259 - 0.294
Sanidine	1.522 - 1.537	0.005 - 0.008
Sapphire	1.757 - 1.779	0.008
Sapphirine	1.714 - 1.723	0.006 - 0.007
Scapolite	1.540 - 1.579	0.004 - 0.038
Scheelite	1.918 - 1.936	0.016 - 0.017
Scolecite	1.509 - 1.525	0.008 - 0.010
Scorodite	1.738 - 1.816	0.027 - 0.036
Sellaite	1.378 - 1.390	0.012
Serandite	1.674 - 1.71	0.035 - 0.036
Serendibite	1.701 - 1.706	0.005
Shomiokite-(Y)	1.528 - 1.531	0.003
Shortite	1.531 - 1.570	0.039
Siderite	1.633 - 1.875	0.240 - 0.242
Sillimanite	1.653 - 1,684	0.016 - 0.023
Simpsonite	1.976 - 2.045	0.020
Sinhalite	1.665 - 1.712	0.036 - 0.039
Smithsonite	1.610 - 1.850	0.225
Sodalite	1.480 - 1.483	0.000
Spessartine	1.790 - 1.820	0.000
Sphalerite	2.368 - 2.371	0.000
Spherocobaltite	1.885 - 1.600	0.285
Spinel	1.708 - 1.735	0.000
Spodumene	1.653 - 1.682	0.014 - 0.016
Staurolite	1.736 - 1.762	0.009 - 0.015
Stibiotantalite	2.374 - 2.457	0.083
Stolzite	2.18 - 2.27	0.080 - 0.090
Sugilite	1.607 - 1.611	0.003 - 0.004
Sussexite	1.67 - 1.73	0.062
Taaffeite	1.717 - 1.730	0.00475
Tanzanite	1.690 - 1.705	0.008 - 0.013
Thaumasite	1.464 - 1.507	0.039
Tiger's eye	1.534 - 1.540	0.009
Titanite / Sphene	1.885 - 2.034	0.100 - 0.192
Topaz	1.606 - 1.643	0.008 - 0.010
Topazolite	1.850 - 1.899	0.000
Tourmaline	1.603 - 1.666	0.006 - 0.080
Tremolite	1.599 - 1.637	0.017 - 0.028
Triphylite	1.689 - 1.702	0.006 - 0.008
Triplite	1.65 - 1.68	0.030
Tsavorite	1.735 - 1.744	0.000
Tugtupite	1.496 - 1.502	0.006
Turquoise	1.610 - 1.650	0.040
Ussingite	1.504 - 1.545	0.039 - 0.041
Uvarovite	1.860 - 1.870	0.000
Vaeyrynenite	1.638 - 1.667	0.026 - 0.027
Viridine	1.634 - 1.643	0.003 - 0.007
Vlasovite	1.607 - 1.628	0.019 - 0.021
Wavellite	1.518 - 1.561	0.025 - 0.026
Whewellite	1.489 - 1.651	0.16
Willemite	1.690 - 1.724	0.028
Witherite	1.529 - 1.677	0.148
Wulfenite	2.280 - 2.405	0.122
Xenotime-(Y)	1.720 - 1.827	0.095
Xonotlite	1.583 - 1.595	0.012
Yugawaralite	1.490 - 1.509	0.009
Zektzerite	1.582 - 1.584	0.002
Zircon	1.777 - 2.025	0.047 - 0.055
Zoisite	1.685 - 1.725	0.006 - 0.018