often coalesced with hornblende, rarely in crystalline slates, eclogite, amphibolite, mica 
and chlorite-slates. 
(g ) Uralitc (Smaragdite in part) has the composition of honddende but has a 
cleavage similar to augite. It is a product of the decomposition of augite and diallage. 
It occurs in gabbros and serpentine as well as augite porphyry. 
TABLE XVL 
Colors of 
pola riza- 
ti07l. 
Color and 
index of re 
fraction. 
Structnre. 
Association 
1 Inclu- 
sions. 
! — 
Very bril- 
Citron yel- 
low, yel- 
In long mi- 
With 
V ery 
liant, yel- 
lowish 
nute columns 
quartz, or- 
j poor. 
low to red. 
green. 
in chloritic 
thoclase, 
1 Fluid 
f-=1.72- 
substance or 
plagio - 
! inclu- 
1 . 75 . Ple- 
in pseudo - 
clase. 
isions. 
ochroism 
rather 
strong in 
thick col 
ufnns. 
a=-pale 
yellow, 
b=yellow- 
ish green 
C=green- 
ish yellow. 
6 >c>a. 
morphs, rare- 
ly in grains. 
i 
j 
I 
horn - 
blende, bi- 
otite, aug- 
ite and 
chlorite. 
' 
j 
Altera- 
tions 
Occurrence 
Secondary 
frequently 
as decom 
position 
product of 
feldspar, 
horn- 
blendes, 
biotite, 
rarely of 
augite in 
eruptives 
& crystal- 
line slates. 
In the lat 
ter also as 
primary. 
Re7narks. 
Similar to au- 
gite. Charac- 
teristic is the 
yellow color, 
strong refrac- 
tion and vivid 
colors of po- 
larization. 
i-i^; acute wedge-shaped sections. 
Not bril- 
liant. 
Faint yel- 
low, red- 
dish 
! brown to 
I colorless, 
j Pleochro 
I ism rather 
j strong in 
■dark varie- 
I ties, a-= 
j reddish 
I brown, 
C=green- 
ish yellow 
Very bril 
liant, ir- 
ridescent. 
Colorless 
or colored 
by iron. 
Surface of sec- 
tion rough. 
One of the 
first minerals 
to form in 
eruptive 
rocks. 
With 
quartz 
plagio 
clase. horn- 
blende, au 
gite, bio- 
tite. chlor- 
ite, quartz 
and other 
I accessory 
minerals. 
In minute 
grains and 
needles, rare- 
!]y in crystals. 
Rarely 
with clas- 
tic compo- 
nents, as 
quartz 
grains or 
scales of 
mica. 
Very 
poor. 
Rarely |As prims - 
pseudo- |ry accesso- 
morphs j ry in 
of cal- I eruptives. 
granite, 
syenite 
phonolite, 
schists, 
etc. 
Andesite 
diorile. 
; cite af- 
I ter ti 
itanite. 
Fluid 
inclu- 
sions. 
As a sim 
pie rock, 
granular 
or massive, 
Easily recog 
nized” by the 
wedge- 
shaped sec- 
tions and 
rough surface. 
