Note on Titaniferous Pyroxene. — A.' N.' Winchell. 309 
NOTE ON TITANIFEROUS PYROXENE. 
By Alexander N. Winchell, Butte, Montana. 
It has been stated by the writer* that "so far as known this 
element [titanium] has no effect on the optic angle [of pyrox- 
ene] , titanaugite having as large an angle as ordinary augite." 
After some search the attempt to verify in the literature 
the last phrase of the above quotation has failed, perhaps for 
lack of ample library facilities. However, the whole purport 
of the quotation is admirably supported by the recent work of 
G. Becker, f who, while making primarily a chemical study, 
has also' investigated the optic properties of a titaninrous pyr- 
oxene from the basanyte (rich in olivine, and poor in feldspar) 
of Kilimanjaro, Africa. Becker has apparently made very 
careful analysis, without, however, determining the percentages 
of alkalies present. His results may be tabulated as follows, 
with certain others introduced for comparison : 
SiOo 
TiOo 
AI2O3 
Fe203 ... 
FeO 
MnO 
MgO 
CaO 
Na20 
K2O 
Ignition. 
Total. 
I. 
II. 
III. 
44.89 
4505 
48.34 
2.39 
4.39 
1.98 
, 3.93 
.16 
2.90 
2.72 
5.50 
4.68 
10.54 
14.90 
1.58 
15.15 
14.15 
12.79 
11.34 
22.13 
10.72 
1.27 
.78 
.13 
15.10 
.11 
99.50 
99.63 
98.49 
118° 11' 
13°— 62°+ 
62° 20' 
60° 28' 
3.36 
3.316+ 
2 E 
2 Ha 
2 Va 
Spr. Gr.... 
I. Pyroxene from basanyte of Kilimanjaro. G. Becker, an- 
alyst, 
n. Pyroxene from olivine diabase of Pigeon Point, Minne- 
sota. A. N. Winchell, analyst. Loc. cit. 
* American Geologist, vol. xxvi, p. 203. 
t GusTAV Becker. Zur Kenntniss der Sesquoixyd — und titanhaltigen 
Augite. Inaugural-Dissertation. Universitats Erlangen. 3 902. 
