Chemistry Reference
In-Depth Information
Indices
balsam1,54
quartz
Birefringence
Color
Alterations
Name
Chemical formula
crystalline forms − cleavages − twins
position of the indicatrix
Uniaxial/
Biaxial
+/−
1st order
2d − 3rd
orders:
bright
colors
higher
orders:
whashed
colors
tourmaline
garnet
0,009
0,018
0,054
Tourmaline
Na(Fe, Mg, Mn, Li)
3
AI
6
Si
6
O
18
(OH)
4
(BO
3
)
3
Trig
green
(blue,
colorless
zoned
inverse
pleochroisme
longitudinal section
U−
ε
transversal fractures
basal section
negative elongation
hex
longitudinal section
Apatite
Ca
5
(PO
4
)
3
(F, CI, OH)
Colorless
U−
ε
basal section
negative elongation
Zircon
ZrSio
4
tetr
Colorless
U+
ε
(pleochroic
halos)
basal section
positive elongation
60
°
Titanite
CaTiSiO
4
(O,OH,F)
mnocl
γ
α
brownish
(greenish,
pink
brown yellow)
B+
51
°
tetr
Rutile
TiO
2
grains
acicular crystals
red brown
yellow brown
green brown
U+
ε
positive elongation
sagenite
cubes − octaedra
octaedral cleavage
Spinel
R
2+
OR
3+
2
O
3
R
2+
= Fe
2+
,
Mg, Zn, Mn
R
3+
= Al, Fe
3+
, Cr
cub
Colorless
blue green
green
brownish
red brown
opaque
Figure 3.39
Summary of the characters of the accessory minerals.
