Chemistry Reference
In-Depth Information
Birefringence
1st order
Name
Chemical formula
Indices
Uniaxial/
Biaxial
+/−
crystalline forms - cleavages - twins
position of the indicatrix
Color
Alterations
higher
orders:
whashed
colors
2d - 3rd
orders:
bright
colors
balsam 1,54
quartz
tourmaline
garnet
0
0,009
0,018
0,054
Gypsum
CaSO
4
2H
2
O
mnocl
α
colorless
B+
(2V=58˚)
38°
γ
β
127°30'
crossection parallel
to the (010) clivages plane
118°
γ
Anhydrite
CaSO
4
γ
orthor
(001)
(001)
colorless
B+
(2V=42−44˚)
β
α
colorless
Barytine
BaSO
4
tabular, lamellar, radiating agregates
orthor
γ
section along
(001) plane
(100)
B+
(2V=36
−38˚)
α
(001)
78°
β
section transversal to the plate
Octaedral (111) cleavage
Fluorite
CaF
2
cub
colorless
(purplish)
negative relief !
Blende
ZnS
cub
(110) cleavage
yellowish
yellow brown
red brown
Scheelite
CaWO
3
tetr
granular, no cleavage
U+
colorless
yellowish
brownish
Cassitérite
Sno
2
quadr
U+
colorless
red brown
green brown
zoned
ε
Figure 3.41
Summary of the characters of sedimentary and ore minerals.
