EKHI

Materials

Curve 1

Temperature K: ~298 Wavelength Range, µm: 1.08-6.78 Geometry θ'ω': ~0°~0° Composition (weight percent), Specifications, and Remarks: CaSO₄·2H₂O (0.648 mm thick); selenite, hydrated, monoclinic crystal; cleavage parallel to b-axis.

Wavelength / 𝜇m	Transmittance /	Temperature / K
1.08	0.817
1.25	0.808
1.33	0.801
1.35	0.76
1.35	0.734
1.41	0.709
1.49	0.68
1.55	0.68
1.58	0.689
1.61	0.731
1.71	0.746
1.84	0.71
1.93	0.579
1.96	0.456
2.05	0.44
2.08	0.444
2.23	0.523
2.3	0.486
2.37	0.436
2.52	0.183
2.71	0.065
2.79	0.042
2.89	0.029
2.98	0.024
3.08	0.027
3.2	0.037
3.35	0.08
3.53	0.171
3.66	0.269
3.97	0.386
4.07	0.354
4.19	0.277
4.23	0.233
4.36	0.134
4.38	0.09
4.44	0.031
4.56	0.006
4.69	0.0
4.74	0.014
4.87	0.056
5.13	0.11
5.24	0.119
5.44	0.119
5.58	0.081
5.66	0.027
5.8	0.019
6.0	0.015
6.14	0.009
6.43	0.006
6.78	0.003

Curve 2

Temperature K: ~298 Wavelength Range, µm: 1.33-2.75 Geometry θ'ω': ~0°~0° Composition (weight percent), Specifications, and Remarks: Similar to curve 1 specimen and conditions except thickness 2.57 mm.

Wavelength / 𝜇m	Transmittance /
1.33	0.735
1.39	0.613
1.4	0.604
1.5	0.454
1.58	0.505
1.66	0.549
1.81	0.524
1.88	0.351
1.95	0.2
2.08	0.192
2.18	0.178
2.27	0.156
2.4	0.089
2.5	0.055
2.75	0.024

Curve 3

Temperature K: ~298 Wavelength Range, µm: 1.11-7.47 Geometry θ'ω': ~0°~0° Composition (weight percent), Specifications, and Remarks: CaSO₄ (0.656 mm thick); anhydrite, orthorhombic crystal, cleavage parallel to c-axis.

Wavelength / 𝜇m	Transmittance /	Temperature / K
1.11	0.676
1.28	0.765
1.33	0.801
1.54	0.856
1.69	0.893
1.83	0.872
1.92	0.851
2.12	0.863
2.26	0.863
2.43	0.867
2.74	0.869
2.88	0.827
3.06	0.773
3.23	0.763
3.34	0.778
3.54	0.797
3.68	0.808
3.94	0.781
4.07	0.649
4.22	0.452
4.34	0.194
4.44	0.105
4.53	0.099
4.6	0.106
4.74	0.231
4.8	0.366
4.89	0.44
4.95	0.562
5.02	0.617
5.13	0.688
5.26	0.72
5.44	0.66
5.51	0.591
5.64	0.5
5.76	0.477
5.87	0.459
5.95	0.448
6.07	0.338
6.14	0.289
6.27	0.369
6.39	0.401
6.49	0.355
6.56	0.299
6.65	0.353
6.69	0.408
6.85	0.329
6.93	0.237
7.04	0.126
7.09	0.052
7.26	0.036
7.47	0.012

Curve 1

Temperature K: ~298 Wavelength Range, µm: 1.29-12.2 Geometry θ θ' ω': ~0°~0° Composition (weight percent), Specifications, and Remarks: AZURITE, 2CuCO₃·Cu(OH)₂; translucent, sample cut parallel to c-axis; 0.35 mm thick.

Wavelength / 𝜇m	Transmittance /
1.29	0.771
1.45	0.775
1.64	0.784
1.86	0.805
2.13	0.819
2.25	0.779
2.41	0.709
2.5	0.658
2.63	0.644
2.72	0.627
2.81	0.659
2.88	0.676
3.0	0.673
3.06	0.704
3.26	0.742
3.39	0.761
3.54	0.775
3.7	0.8
3.97	0.804
4.24	0.814
4.51	0.802
4.78	0.787
5.0	0.78
5.25	0.78
5.47	0.778
5.66	0.771
5.9	0.789
6.09	0.777
6.29	0.784
6.47	0.782
6.71	0.8
6.91	0.783
7.11	0.775
7.26	0.782
7.38	0.795
7.62	0.765
7.78	0.765
8.03	0.764
8.19	0.74
8.34	0.745
8.48	0.736
8.61	0.742
8.77	0.741
8.94	0.743
9.09	0.729
9.25	0.709
9.41	0.71
9.65	0.684
9.79	0.677
10.0	0.673
10.1	0.657
10.3	0.6
10.4	0.572
10.6	0.498
10.8	0.469
10.9	0.447
11.0	0.43
11.2	0.37
11.5	0.267
11.7	0.219
12.0	0.085
12.2	0.027

Curve 1

Temperature K: ~298 Wavelength Range, µm: 1.04-10.1 Geometry: ~0°~0° Composition (weight percent), Specifications, and Remarks: GOETHITE, FeO(OH); section ground parallel to b-axis to thickness 0.15 mm; opaque, black metallic luster.

Wavelength / 𝜇m	Transmittance /
1.04	0.019
1.25	0.141
1.4	0.191
1.6	0.21
1.97	0.236
2.12	0.254
2.26	0.27
2.4	0.28
2.51	0.257
2.74	0.2
2.86	0.151
3.04	0.138
3.24	0.14
3.4	0.163
3.67	0.187
3.96	0.208
4.21	0.223
4.45	0.217
4.74	0.222
5.01	0.22
5.25	0.224
5.6	0.22
5.78	0.22
6.04	0.235
6.26	0.241
6.54	0.251
6.87	0.271
7.25	0.282
7.48	0.263
7.74	0.197
8.03	0.158
8.24	0.126
8.42	0.103
8.75	0.066
8.92	0.052
9.06	0.04
9.22	0.051
9.38	0.063
9.56	0.064
9.75	0.042
10.0	0.023
10.1	0.009

Curve 1

Temperature K: ~298 Wavelength Range, µm: 1.47-8.43 Geometry: ~0°~0° Composition (weight percent), Specifications, and Remarks: BAUXITE, Al₂O(OH)₄; 0.11 mm thick; chocolate brown color.

Wavelength / 𝜇m	Transmittance /
1.47	0.006
1.68	0.025
1.8	0.045
1.95	0.069
2.08	0.095
2.21	0.117
2.38	0.134
2.52	0.11
2.71	0.057
2.8	0.026
2.92	0.006
3.04	0.0
3.21	0.004
3.37	0.008
3.51	0.015
3.66	0.028
3.95	0.064
4.21	0.072
4.36	0.062
4.49	0.038
4.62	0.026
4.73	0.017
4.88	0.025
5.0	0.037
5.21	0.054
5.46	0.058
5.65	0.045
5.82	0.045
6.05	0.055
6.28	0.07
6.46	0.078
6.65	0.066
6.85	0.046
7.04	0.035
7.22	0.045
7.37	0.053
7.56	0.063
7.75	0.064
7.88	0.054
8.01	0.035
8.24	0.019
8.43	0.009

Curve 2

Temperature K: ~298 Wavelength Range, µm: 1.10-9.45 Geometry: ~0°~0° Composition (weight percent), Specifications, and Remarks: BRUCITE, Mg(OH)₂; 0.05 mm thick.

Wavelength / 𝜇m	Transmittance /
1.1	0.723
1.48	0.763
1.72	0.735
1.97	0.64
2.06	0.52
2.21	0.37
2.27	0.33
2.39	0.295
2.48	0.279
2.56	0.3
2.68	0.331
2.86	0.381
3.0	0.49
3.17	0.632
3.32	0.694
3.47	0.718
3.67	0.746
4.1	0.745
4.46	0.713
4.56	0.695
4.57	0.695
4.72	0.669
4.96	0.654
5.07	0.655
5.2	0.661
5.39	0.662
5.56	0.655
5.66	0.644
5.87	0.622
5.97	0.598
6.0	0.577
6.13	0.586
6.24	0.585
6.37	0.584
6.61	0.585
6.87	0.585
7.06	0.586
7.4	0.526
7.54	0.5
7.95	0.395
8.15	0.36
8.47	0.293
8.88	0.111
9.03	0.051
9.19	0.015
9.45	0.0

Curve 3

Temperature K: ~298 Wavelength Range, µm: 1.23-5.75 Geometry: ~0°~0° Composition (weight percent), Specifications, and Remarks: BRUCITE, Mg(OH)₂; 0.19 mm thick.

Wavelength / 𝜇m	Transmittance /
1.23	0.296
1.3	0.327
1.48	0.357
1.6	0.367
1.7	0.374
1.81	0.385
1.95	0.392
2.12	0.403
2.26	0.391
2.39	0.328
2.56	0.298
2.64	0.289
2.82	0.215
2.89	0.177
2.95	0.14
3.02	0.135
3.11	0.157
3.19	0.176
3.28	0.203
3.43	0.17
3.5	0.138
3.68	0.191
3.77	0.252
3.82	0.211
3.93	0.146
4.0	0.1
4.14	0.135
4.23	0.178
4.4	0.273
4.46	0.301
4.61	0.315
4.74	0.326
4.97	0.279
5.13	0.2
5.23	0.116
5.35	0.051
5.46	0.019
5.61	0.007
5.75	0.006

Curve 4

Temperature K: ~298 Wavelength Range, µm: 1.08-8.23 Geometry: ~0°~0° Composition (weight percent), Specifications, and Remarks: DIASPORE, AlO(OH); cleavage piece parallel to b-axis; 0.18 mm thick.

Wavelength / 𝜇m	Transmittance /
1.08	0.313
1.28	0.342
1.45	0.362
1.59	0.35
1.72	0.259
1.8	0.223
1.95	0.224
2.09	0.227
2.26	0.2
2.4	0.185
2.55	0.169
2.74	0.156
2.92	0.147
3.08	0.141
3.21	0.146
3.37	0.155
3.5	0.166
3.64	0.175
3.81	0.18
3.95	0.187
4.12	0.186
4.27	0.189
4.44	0.192
4.75	0.19
5.0	0.19
5.26	0.182
5.45	0.16
5.66	0.134
5.88	0.108
6.07	0.097
6.35	0.075
6.48	0.052
6.58	0.034
6.81	0.026
7.07	0.024
7.26	0.017
7.52	0.01
7.83	0.009
8.04	0.01
8.23	0.007

Curve 5

Temperature K: ~298 Wavelength Range, µm: 1.27-6.07 Geometry: ~0°~0° Composition (weight percent), Specifications, and Remarks: HYDRARGILLITE, Al(OH)₃, stalactitic mass; 0.02 mm thick.

Wavelength / 𝜇m	Transmittance /
1.27	0.087
1.38	0.122
1.54	0.161
1.61	0.176
1.81	0.189
1.97	0.177
2.06	0.162
2.2	0.14
2.34	0.112
2.49	0.063
2.7	0.024
2.85	0.007
3.04	0.0
3.23	0.005
3.37	0.015
3.51	0.022
3.65	0.035
3.81	0.043
3.94	0.054
4.17	0.063
4.48	0.056
4.77	0.04
5.0	0.031
5.24	0.025
5.46	0.026
5.66	0.015
5.85	0.009
6.07	0.0

Curve 6

Temperature K: ~298 Wavelength Range, µm: 1.04-8.71 Geometry: ~0°~0° Composition (weight percent), Specifications, and Remarks: MANGANITE, MnO(OH); opaque, orthorhombic, ground parallel to m; 0.08 mm thick.

Wavelength / 𝜇m	Transmittance /
1.04	0.019
1.23	0.146
1.39	0.206
1.59	0.214
1.77	0.211
2.12	0.193
2.4	0.165
2.5	0.154
2.7	0.146
2.89	0.132
3.03	0.123
3.22	0.118
3.37	0.118
3.53	0.12
3.64	0.12
3.95	0.122
4.23	0.122
4.45	0.124
4.73	0.129
5.0	0.131
5.25	0.135
5.38	0.14
5.48	0.147
5.77	0.15
5.98	0.14
6.27	0.143
6.57	0.152
6.77	0.16
6.98	0.16
7.23	0.146
7.46	0.144
7.64	0.135
8.03	0.098
8.42	0.062
8.71	0.043

Curve 1

Temperature K: ~298 Wavelength Range, µm: 1.13-7.12 Geometry θθ' ω': ~0°~0° Composition (weight percent), Specifications, and Remarks: DATOLIGHT, Ca(BOH)SiO₄; ground to 0.23 mm thick.

Wavelength / 𝜇m	Transmittance /
1.13	0.308
1.27	0.32
1.45	0.347
1.6	0.379
1.84	0.416
2.0	0.415
2.15	0.347
2.25	0.338
2.4	0.332
2.53	0.318
2.64	0.299
2.74	0.278
2.89	0.283
3.06	0.367
3.24	0.427
3.54	0.454
3.83	0.464
4.1	0.408
4.32	0.351
4.48	0.27
4.63	0.207
4.72	0.158
4.87	0.126
4.98	0.1
5.0	0.096
5.13	0.082
5.3	0.065
5.42	0.078
5.66	0.098
5.75	0.078
5.85	0.059
5.96	0.044
6.16	0.033
6.35	0.036
6.7	0.045
6.9	0.031
7.12	0.008

Curve 2

Temperature K: ~298 Wavelength Range, µm: 1.10-7.27 Geometry θθ' ω': ~0°~0° Composition (weight percent), Specifications, and Remarks: GLAUBERITE, Na₂SO₄·CaSO₄; monoclinic; cleavage section parallel to e-axis; 1.26 mm thick.

Wavelength / 𝜇m	Transmittance /
1.1	0.675
1.43	0.758
1.58	0.775
1.84	0.794
2.08	0.791
2.34	0.778
2.5	0.759
2.69	0.697
2.86	0.651
3.0	0.648
3.04	0.655
3.19	0.697
3.33	0.727
3.48	0.746
3.64	0.736
3.93	0.618
3.93	0.618
4.05	0.466
4.37	0.067
4.44	0.018
4.61	0.01
4.74	0.136
4.86	0.259
5.0	0.426
5.23	0.589
5.44	0.417
5.56	0.3
5.65	0.288
5.77	0.3
5.87	0.308
5.97	0.2
6.08	0.103
6.17	0.046
6.3	0.042
6.38	0.067
6.46	0.117
6.59	0.134
6.68	0.129
6.85	0.103
7.03	0.056
7.27	0.011

Curve 3

Temperature K: ~298 Wavelength Range, µm: 1.03-5.68 Geometry θθ' ω': ~0°~0° Composition (weight percent), Specifications, and Remarks: HEULANDITE, H₄CaAl₂Si₆O₁₈ + 3H₂O; section ground parallel to b-axis; semitransparent; ~0.21 mm thick.

Wavelength / 𝜇m	Transmittance /
1.03	0.5
1.25	0.532
1.38	0.541
1.46	0.563
1.59	0.583
1.69	0.574
1.8	0.528
1.96	0.5
2.05	0.521
2.1	0.546
2.21	0.508
2.39	0.365
2.54	0.215
2.75	0.072
2.86	0.03
3.0	0.02
3.15	0.032
3.22	0.046
3.37	0.144
3.53	0.288
3.69	0.398
3.8	0.482
3.95	0.456
4.23	0.338
4.36	0.275
4.47	0.233
4.64	0.214
4.87	0.192
5.0	0.158
5.14	0.124
5.24	0.102
5.46	0.067
5.68	0.036

Curve 4

Temperature K: ~298 Wavelength Range, µm: 1.03-5.92 Geometry θθ' ω': ~0°~0° Composition (weight percent), Specifications, and Remarks: Similar to above specimen and conditions; transparency and homogeneity different.

Wavelength / 𝜇m	Transmittance /
1.03	0.299
1.3	0.286
1.34	0.256
1.38	0.243
1.62	0.262
1.71	0.256
1.94	0.234
2.21	0.226
2.41	0.164
2.54	0.101
2.7	0.069
2.89	0.04
3.07	0.02
3.37	0.057
3.51	0.1
3.63	0.143
3.97	0.2
4.08	0.198
4.22	0.167
4.35	0.131
4.44	0.122
4.54	0.101
4.84	0.08
5.03	0.063
5.2	0.046
5.51	0.027
5.73	0.013
5.92	0.006

Curve 5

Temperature K: ~298 Wavelength Range, µm: 1.23-8.49 Geometry θθ' ω': ~0°~0° Composition (weight percent), Specifications, and Remarks: NATROLITE, Na₂Al₂Si₃O₁₀ + 2H₂O, subtranslucent; orthorhombic section ground parallel to m; 0.11 mm thick.

Wavelength / 𝜇m	Transmittance /
1.23	0.205
1.26	0.256
1.36	0.324
1.46	0.28
1.54	0.305
1.66	0.359
1.83	0.349
1.92	0.315
2.02	0.326
2.09	0.354
2.2	0.396
2.41	0.375
2.5	0.332
2.69	0.215
2.87	0.094
2.96	0.049
3.01	0.025
3.16	0.032
3.32	0.114
3.47	0.197
3.66	0.341
3.9	0.433
4.18	0.428
4.33	0.332
4.47	0.242
4.59	0.236
4.73	0.259
4.86	0.294
4.99	0.348
5.24	0.363
5.44	0.309
5.64	0.217
5.74	0.175
5.87	0.115
5.97	0.064
6.05	0.02
6.26	0.034
6.45	0.098
6.64	0.147
6.84	0.153
7.04	0.145
7.23	0.125
7.39	0.101
7.63	0.084
7.82	0.054
8.07	0.023
8.26	0.005
8.49	0.002

Curve 6

Temperature K: ~298 Wavelength Range, µm: 1.08-5.95 Geometry θθ' ω': ~0°~0° Composition (weight percent), Specifications, and Remarks: SCOLECITE, CaAl₂Si₃O₁₀ + 3H₂O, perfectly transparent; monoclinic section split parallel to m; 0.565 mm thick.

Wavelength / 𝜇m	Transmittance /
1.08	0.57
1.13	0.593
1.22	0.643
1.36	0.569
1.38	0.541
1.44	0.531
1.51	0.539
1.58	0.583
1.66	0.597
1.82	0.542
1.92	0.434
2.01	0.422
2.11	0.455
2.21	0.415
2.36	0.257
2.57	0.08
2.7	0.03
2.97	0.003
3.11	0.003
3.34	0.015
3.51	0.055
3.65	0.14
3.81	0.175
3.98	0.187
4.07	0.177
4.21	0.105
4.35	0.065
4.48	0.065
4.62	0.057
4.74	0.05
4.88	0.04
5.01	0.035
5.12	0.026
5.26	0.019
5.44	0.008
5.73	0.002
5.95	0.0

Curve 7

Temperature K: ~298 Wavelength Range, µm: 1.09-6.29 Geometry θθ' ω': ~0°~0° Composition (weight percent), Specifications, and Remarks: SERPENTINE, H₄(MgFe)₃Si₂O₉; 0.225 mm thick; massive, subtranslucent.

Wavelength / 𝜇m	Transmittance /
1.09	0.426
1.29	0.432
1.43	0.438
1.52	0.462
1.6	0.492
1.73	0.5
1.83	0.514
1.98	0.522
2.22	0.505
2.23	0.489
2.38	0.42
2.38	0.397
2.51	0.311
2.69	0.145
2.76	0.074
2.87	0.045
2.93	0.026
3.07	0.033
3.19	0.058
3.33	0.104
3.36	0.122
3.5	0.171
3.66	0.246
3.96	0.355
4.22	0.373
4.51	0.372
4.77	0.326
4.88	0.273
5.0	0.24
5.14	0.225
5.29	0.224
5.36	0.2
5.57	0.129
5.77	0.079
5.98	0.036
6.29	0.016

Curve 8

Temperature K: ~298 Wavelength Range, µm: 1.08-9.14 Geometry θθ' ω': ~0°~0° Composition (weight percent), Specifications, and Remarks: SERPENTINE, H₄(MgFe)₃Si₂O₉; 0.08 mm thick.

Wavelength / 𝜇m	Transmittance /
1.08	0.783
1.24	0.79
1.46	0.794
1.59	0.805
1.79	0.817
2.07	0.828
2.23	0.8
2.38	0.765
2.54	0.712
2.75	0.554
2.82	0.398
2.89	0.306
3.0	0.3
3.08	0.326
3.17	0.381
3.23	0.438
3.36	0.513
3.53	0.641
3.65	0.675
3.97	0.746
4.2	0.727
4.46	0.732
4.65	0.714
4.77	0.695
4.88	0.662
5.0	0.636
5.27	0.621
5.37	0.6
5.48	0.559
5.67	0.474
5.86	0.398
6.09	0.307
6.19	0.276
6.27	0.242
6.46	0.215
6.67	0.198
6.83	0.198
7.05	0.188
7.26	0.177
7.4	0.168
7.56	0.173
7.73	0.177
7.89	0.149
7.98	0.135
8.05	0.109
8.21	0.098
8.37	0.075
8.5	0.046
8.71	0.053
8.89	0.05
9.0	0.028
9.14	0.0

Curve 9

Temperature K: ~298 Wavelength Range, µm: 1.11-1.73 Geometry θθ' ω': ~0°~0° Composition (weight percent), Specifications, and Remarks: STILBITE, CaAl₂Si₆O₁₆ + 6H₂O, transparent; cut perpendicular to optic axis; 0.11 mm thick.

Wavelength / 𝜇m	Transmittance /
1.11	0.773
1.25	0.779
1.34	0.757
1.47	0.747
1.56	0.784
1.56	0.8
1.61	0.815
1.73	0.8

Curve 10

Temperature K: ~298 Wavelength Range, µm: 1.31-8.89 Geometry θθ' ω': ~0°~0° Composition (weight percent), Specifications, and Remarks: TALC, H₂Mg₃Si₄O₁₂; 0.06 mm thick.

Wavelength / 𝜇m	Transmittance /
1.31	0.808
1.48	0.819
1.62	0.83
1.79	0.833
2.0	0.84
2.17	0.838
2.42	0.835
2.72	0.837
3.08	0.829
3.55	0.833
3.74	0.835
4.0	0.844
4.32	0.842
4.52	0.842
4.81	0.8
5.0	0.742
5.18	0.649
5.3	0.587
5.46	0.516
5.62	0.51
5.79	0.526
5.89	0.514
5.97	0.479
6.1	0.578
6.19	0.683
6.4	0.7
6.63	0.682
6.79	0.667
7.0	0.612
7.07	0.587
7.2	0.537
7.34	0.548
7.53	0.534
7.72	0.5
7.84	0.475
7.98	0.406
8.13	0.313
8.25	0.24
8.38	0.157
8.52	0.078
8.66	0.022
8.89	0.0

Curve 1

Temperature K: ~298 Wavelength Range, µm: 1.27-7.71 Geometry θ θ' ω: ~0°~0° Composition (weight percent), Specifications, and Remarks: ANGLESITE, PbSO₄, from Monte Poni, Sardinia (0.7 mm thick); translucent section parallel to m.

Wavelength / 𝜇m	Transmittance /
1.27	0.25
1.43	0.27
1.61	0.274
1.82	0.284
2.09	0.308
2.38	0.332
2.7	0.333
3.02	0.326
3.2	0.324
3.37	0.329
3.51	0.336
3.68	0.341
3.93	0.347
4.05	0.316
4.2	0.215
4.33	0.126
4.45	0.063
4.58	0.041
4.74	0.017
4.86	0.009
5.0	0.007
5.1	0.033
5.21	0.083
5.43	0.232
5.63	0.309
5.82	0.296
6.0	0.22
6.18	0.161
6.27	0.115
6.33	0.085
6.46	0.068
6.57	0.073
6.65	0.058
6.83	0.069
7.0	0.1
7.19	0.134
7.32	0.132
7.52	0.065
7.71	0.014

Curve 2

Temperature K: ~298 Wavelength Range, µm: 1.28-7.93 Geometry θ θ' ω: ~0°~0° Composition (weight percent), Specifications, and Remarks: BARITE, BaSO₄, from Cheshire, Conn. (0.25 mm thick); orthorhombic; section parallel to c-axis.

Wavelength / 𝜇m	Transmittance /
1.28	0.153
1.68	0.178
1.88	0.197
2.12	0.214
2.37	0.228
2.53	0.235
2.7	0.243
2.87	0.242
3.0	0.24
3.17	0.249
3.49	0.269
3.95	0.293
4.07	0.269
4.24	0.218
4.36	0.13
4.43	0.098
4.46	0.083
4.61	0.069
4.66	0.086
4.76	0.104
4.86	0.125
5.0	0.184
5.25	0.252
5.65	0.246
5.79	0.252
5.97	0.246
6.06	0.218
6.2	0.172
6.28	0.167
6.39	0.172
6.47	0.163
6.58	0.161
6.61	0.186
6.71	0.224
6.78	0.284
6.96	0.3
7.23	0.268
7.39	0.154
7.56	0.049
7.75	0.015
7.93	0.004

Curve 3

Temperature K: ~298 Wavelength Range, µm: 1.28-7.37 Geometry θ θ' ω: ~0°~0° Composition (weight percent), Specifications, and Remarks: CELESTITE, SiSO₄; from Lampasao, Texas (0.67 mm thick); cleavage parallel to c-axis.

Wavelength / 𝜇m	Transmittance /
1.28	0.67
1.68	0.665
2.09	0.658
2.23	0.654
2.38	0.66
2.52	0.658
2.68	0.655
2.85	0.631
3.04	0.619
3.23	0.609
3.52	0.625
3.79	0.618
3.96	0.6
4.06	0.51
4.22	0.374
4.32	0.22
4.46	0.1
4.6	0.083
4.71	0.096
4.75	0.125
4.85	0.185
5.0	0.316
5.12	0.4
5.26	0.5
5.44	0.496
5.68	0.493
5.87	0.457
6.06	0.323
6.27	0.194
6.42	0.148
6.55	0.157
6.66	0.269
6.84	0.371
6.97	0.3
7.06	0.267
7.22	0.124
7.37	0.036

Curve 4

Temperature K: ~298 Wavelength Range, µm: 1.18-2.82 Geometry θ θ' ω: ~0°~0° Composition (weight percent), Specifications, and Remarks: POTASSIUM ALUM, K₂SO₄Al₂(SO₄)₃ + 24H₂O, transparent; cut perpendicular to optic axis; 0.085 mm thick.

Wavelength / 𝜇m	Transmittance /
1.13	0.505
1.3	0.5
1.38	0.456
1.47	0.424
1.59	0.48
1.72	0.5
1.81	0.488
1.92	0.448
1.97	0.405
2.01	0.427
2.09	0.452
2.21	0.468
2.38	0.423
2.49	0.3
2.63	0.193
2.68	0.146
2.77	0.08
2.8	0.067
2.82	0.048

The Infra-Red Absorption and Reflection Spectra of KHF2 and of KDF2 [2]

The Infra-Red Absorption and Reflection Spectra of KHF₂ and of KDF₂ [2]