Name. 
Chem. 
Comp, and 
reactions. 
Specif. 
Gray. 
Cleavage. 
Usual com- 
binations Sf 
form of Secs. 
Twins 
Opticial 
determinants 
Dcmble 
Refract. 
Colors of 
Polariza- 
tion. 
f. Acmite. 
Na2 (Fe2 ) 
3 * 53 - 
Complete 
In grains or 
i-i 
As augite. 
As 
As 
Si, 0 ,, 
3-55 
I 87°, 
long flat- 
fre- 
augite. 
augite. 
incom- 
tened col- 
quent. 1 
plete 
umns 
Pleochro- 
i-i. 
(planes i-i 
ism rath- 
being 
i 
1 
er strong. 
largest.) 
1 
1 
C=dark 
■ 
I . i-i . i-F 
i 
brown. 
■ 
1 
1 
1 
a= 
1 
1 
brownish 
g. Wallas- 
Ca Si 0 ., 
2. 78- 
Parallel 
1=87° 
do 
Opt. axis 
Positive, 
green. 
Ionite. 
Completely 
2.91 
i-i, 0 
Almost 
plane 
strong, c 
cf>hf>U 
decompos’d 
and I-i 
always in 
11 i-i^- 
forms an 
separating 
irregular 
Apparent 
angle with 
Very 
galatinous 
flbrous 
axial 
Oof32°-I2^ 
brilliant. 
silica. 
long prisms 
i 
angle = 70° 
a : c--=i2° 
cc. 
Complete 
1 
2 . Horn 
mRSi O., 
31- 
I very 
I . i-i^ . i-i 
Fre- 
Opt. axis 
Negative, 
Less 
blende \ 
n ( R2 ) 0., . 
3-3 
perfect 
and 0 . I or 
quent 
plane || i-F. 
rather less 
brilliant 
Group. ! 
R=Ca, Mg 
with 
I— F almost 
I i-i 
Acute bisec- 
strong than 
than in 
Commondf'i 
Fe. 
angle of 
always in 
trix=a 
augite. 
augite. 
Basaltic 
R2 = (Al,) 
124° iC; 
crystals. 
i 
falls in the 
Extinction : 
yellow. 
Hornblende 
(Fes ). 
i-i and 
Cross sec- 
! 
obtuse 
C: c= about 
green. 
[b. Smar- 
When 
i— i^ 
tions usual- 
angle 
13° (2-18°) 
brown. 
1 agdite 
containing 
imperfect 
ly hexagons 
h=h. Real 
a : c---75° 
1 Compare 
much iron, 
also octago- 
i 
axial angle 
a : a^=29° 
uralite. Oc- 
attacked 
nal, longit. 
about 79°. 
38^- 
curs with 
slightly by 
sections as 
Positive 
c : C=I3- 
omphacite 
acids. 
augite. 
1 
axial angle 
garnet, 
1 
j 
varying 
in green. 
zoisite. and 
with amt 
11-13° in 
; rutile.] 
of Fe. Opt. 
brown 
axis disap- 
hornblende 
i 
Ca Mg3 Si, 
3.026- 
As 
Long 
More 
pears on 
jc. Actino- 
Oi2+CaFe3 
3.16 
above. 
columns 
rarely. 
edge of 
1 lite. 
Si, 0,.2 
fracture 
usually not 
field 
( £ 
(Techer- 
trans- 
terminated 
j 
j| 0 and i-i. 
mak) 
verse. 
I . i-i" 
p<fy 
No Al. 
little iron. 
3MgSi03+ 
I 
I . i-i 
[C: c 15°] 
d. Treino- 
CaSi O3 
2 - 93-3 
as above'. 
long 
lite. 
Preponder- 
slender 
( 6 
Very 
ating 
columns. 
£ £ 
brilliant. 
% 
Mg 0 . 
(See next 
Insoluble. 
table.) 
