TABLE XIK 
Colors 
ofpolar- 
ization. 
do 
In section 
green to 
brown, 
often vio- 
let brown 
in basalt. 
The same 
crystal 
often ex- 
hibiting 
several 
colois. 
Pleochro- 
ism usual- 
ly feeble. 
In phono- 
lite it may 
be strong. 
c>a>b. 
do 
do 
Very 
bril- 
liant* 
Color 
and Re- 
fraction 
Structure, 
Greenish 
brown. 
Pleochro- 
ism very 
feeble. 
Grass 
3;reen. 
do 
Light 
green — ■ 
colorless. 
Relief 
strong. 
In large 
crystals 
(L O.) 
with zonal 
alt’rnating 
colors. In 
twins 
these 
bands pass 
through; 
both. Oft- 
en with so- 
called 
“hour- 
glass” 
form. when 
sections 
parallel to 
i-i fall into 
I 4 areas. ^ 
Also in 
J columns 
and micro- 
lites(II.O,) 
crystals 
often in 
large ag- 
gregates & 
radial 
groups 
Chiefly 
with pla- 
gioclase, 
nepheline, 
leucite, 
with or 
without 
olivine 
and bio- 
tite. Rare- 
ly with 
ortho- 
clase, horn- 
blende, 
and 
quartz. 
Only as 
large ir- 
regular 
grains. In 
inclusions, 
in fibrous 
and twin 
ning char- 
acters 
much as 
bronzite. 
Often co- 
alesced 
with ordi- 
nary aug- 
ite, horn- 
blende or 
Only in un 
altered 
gr’ins poor 
in inclu- 
sions. Oft- 
en coalesc 
ed with 
horn- 
blende. 
Association 
Inclusions. 
Abundant 
glass inclu- 
sions, apa- 
tite nee- 
dles and 
magnetite. 
Decomposition. 
With pla- 
gioclase, 
common 
augite, ol- 
ivine, 
horn- 
blende, 
and rarely 
with 
quartz. 
(c) With 
quartz, 
horn- 
blende, 
garnet, zo- 
isite, dis- 
thene, and 
rutile. 
(d_) With 
olivine, 
chromite, 
diallage, & 
rhombic 
augite. 
(e) quartz, 
horn- 
blende, 
scapolite, 
plagio- 
clase, and 
titanite. 
Like 
bronzite 
with inclu- 
sions of 
brown 
scales of 
goethite? 
parallel to 
i-i. other- 
wise poor 
in inclu- 
sions. 
(c) Rare, 
fluid and 
rutile nee 
dies. 
(d) Rarely 
glass in- 
clusions. 
Into chlorite, 
calcite, limon- 
ite. epidote 
and quartz, 
ps’udomorphs 
of any of these 
after augite. 
Into opal. 
More rarely 
into horn- 
blende, the 
form being re- 
tained but the 
cleavage that 
of hornblende. 
Into serpen- 
tine with talc 
and chlorite. 
At the ends 
changes into 
dark green 
strongly pie- 
ochroic horn- 
blende fibres. 
Into viridite, 
also serpen- 
tine with for- 
mation of 
chlorite and 
talc. 
Occurrence. 
Later porphy- 
ritic eruptives 
as essential 
and primary, 
in diabase, 
augite ande- 
site, and all 
basalts, also 
andesites, tra- 
chytes. phon- 
olites. Rarely 
in large grains 
in older erupt- 
ives and crys- 
talline slates. 
Primary abun- 
dant in gab- 
bro, norite, 
rare porphyr 
itic eruptives. 
In olivine 
stone and ser- 
pentine. Rare 
in crystalline 
slates. 
(c) In eclcg- 
ite and am- 
phibolite 
(d) In olivine 
stone (prima- 
ry) rarely sec- 
ondary altera- 
tion of garnet. 
(e) In crystal- 
line slates. 
Remarks. 
Easily recog- 
nized by ob- 
liquity of ex- 
tinction of c.‘ 
c. the prismat- 
ic cleavage 
with angle of 
87°, especially 
in cross sec- 
tion. Liable 
to be confused 
with horn 
blende in sec- 
tions inclined 
to c. When 
augite is near- 
ly colorless its 
polarization 
colors are; 
vivid and like 
olivine. 
Often similar 
to bronzite 
in sections or 
plates parallel 
to i-i easily 
recognized. 
Colors lighter 
than in augite 
proper (less 
iron). Differ 
from diallage 
in absence of 
complete 
fracture in 
