Materials
/
Sillimanite
Sillimanite
Refractive Index
1.6635–1.6653
Abbe Number
54.6–62.3
Crystal System
Isotropic (cubic)
Formation
Natural
Dispersion Data
Measured (published fit)
Fits
3
Refraction Fits
Fit #1
Shannon / Cauchy
n
n
=
1.6652
V
D
=
61.1
n
400
450
500
550
600
650
700
750
1.650
1.660
1.670
1.680
1.690
n
2
=
1
+
0.5813
(
λ
2
−
0.010322
)
λ
2
Fit #2
— Specimen fit
Shannon / Cauchy
n
n
=
1.6635
V
D
=
62.3
n
400
450
500
550
600
650
700
750
1.650
1.660
1.670
1.680
1.690
n
2
=
1
+
0.5828
(
λ
2
−
0.010124
)
λ
2
Fit #3
— Specimen fit
Shannon / Cauchy
n
n
=
1.6653
V
D
=
54.6
n
400
450
500
550
600
650
700
750
1.650
1.660
1.670
1.680
1.690
1.700
n
2
=
1
+
0.5832
(
λ
2
−
0.011488
)
λ
2
Absorption Specimens
LED
SUN
I
F
Sillimanite
Myanmar, Mandalay Division, Mogok
LED
SUN
I
F
Sillimanite
Myanmar, Mandalay Division, Mogok (Kyatpyin)
LED
SUN
I
F
Sillimanite
Myanmar, Mandalay Division, Mogok (Kyatpyin)
LED
SUN
I
F
Sillimanite
Sri Lanka, Sabaragamuwa Province, Eheliyagoda
LED
SUN
I
F
Sillimanite
Sri Lanka, Sabaragamuwa Province, Eheliyagoda
LED
SUN
I
F
Sillimanite
Sri Lanka, Sabaragamuwa Province, Kolonne