TABLE XV ILL 
Colors 
ofpolar- 
ization. 
1 Color 
1 and Re- 
fraction. 
Struclu7'e. 
AssociatioJt 
hiclusions . 
Altei'ation. 
Occurrence. 
Re- 
marks. 
As al- 
bite. 
i 
Colorless, 
clear or 
cloudy, 
white to 
gray. 
In large grains 
or crystals oi 
I.O. and in 
minute slen- 
der rods (sec- 
tions of thin 
plates. Zonary 
structure and 
arrangement 
of inclusions. 
Twinning and 
concentric ar- 
rangement (as 
in orthoclase) 
both present. 
With 
quartz, or 
thoclase, 
horn- 
blende, bi- 
otite. aug- 
ite and ol 
ivine. 
Fluid (rarely) 
and frequent- 
[ly glass inclu- 
sions in later 
eruptives; au- 
gite and apa- 
tite microlites 
Usually unal- 
1 tered in later 
and cloudy- 
fibrous in ear- 
• Her eruptives 
Change into 
epidote 
(“saussurite”) 
also to musco- 
vite as in or- 
thoclase and 
nearly all pla- 
gioclase. 
Primary es- 
• sential or ac- 
cessory in 
eruptives. 
granite, dior- 
ite. diabase, 
gabbro, tra- 
chyte, ande- 
site, also in 
basalt, and 
crystalline 
slates. 
As al- 
bite. 
With sail- 
dine, or 
thoclase, 
augite, 
horn- 
blende,bi 
otite and 
quartz. 
do 
Primary es- 
sential in ton- 
alite (quartz 
diorite), in 
andesite, in 
particular, and 
esites, porph- 
yries, syenite, 
also in cryst. 
slates. 
do 
As al- 
bite. 
i 
[ 
do 
Usually un- 
altered. 
do 
Hornblende, 
olivine, dial- 
lage, magne- 
tite, titanic 
iron. Acicu- 
late microlites 
are very abun- 
dant and lie | 
c or the angle 
0: i-i, and 
brown plates 
(ferric oxide 
or brookite?) 
which have 
their long axis 
at right angles! 
to the micro | 
lites, or innu- 
merable mi- 
nute colorless 
or greenish 
grains (epi- I 
dote?) 
In grains and 
large crystals 
I.O. and mi- 
crolites II 0 
When twin’d 
upon both the 
albite and pe- 
r feline type a 
lattice struc- 
ture similar to 
microcline ap- 
.pears, but the 
bands are 
more distinct 
As orthoclase. 
Often into 
epidote and 
muscovite. 
Primary, es- 
sential, in nor- 
ite, gabbro, 
dolerites, es- 
pecially also 
in dacite, ba- 
salts, diorite. 
do 
Usual- 
ly very 
vivid. 
! 
As ortho- 
clase. 
With di- 
allage, hy- 
persthene, 
olivine, 
also with 
quartz, au 
gite, horn- 
blende, 
and bio- 
tite 
do 
Primary es- 
sential in 
eruptives, di- 
orite, gabbro, 
andesites. 
do 
1 
do 
1 
do 
do ! 
i 
1 
i 
i 
1 
j 
i 
1 
With 
horn- 
blende, au- 
gite, bio- 
tite, dial- 
lage, hy- 
persthene 
do 
but no micro- 
lites and 
scales. 
As lab- 
brador- 
te. 
i 
[Colorless, 
clear, as 
labrador-' 
ite. 
As labrador- 
ite. 
! 
j 
i 
1 
With lab- 
radorite, 
augite, hy- 
persthe- 
nite, oliv-' 
ine. 
As oligoclase. 
Usually unal- 
tered, as the 
other plagio- < 
clase species. 1 
1 
c 
( 
Rather rare, 
primary es- 
sential in 
sruptives. In 
basaltic rocks 
and augite an- 
desites, gab- 
bro and norite, 
in crystalline 
>lates,amphib- 
alites, gneiss. 
! 
