536 TOE VOGT 
orthorhombic pyroxene to be reduced about one-tenth, and for the 
monoclinic pyroxene, which throughout contains a little more 
Fe,O;, about one-eighth. This correction, however, is of small 
extent. 
The stoechiometric proportion between MgO and FeO in 
orthorhombic and monoclinic pyroxene from the same rock: 
Marburg...... Te Bronzite t MgO:o.11 FeO 
Weeier 59¢ Diopside 1 MgO:o0.07 FeO 
Ola nen oHlee Vee ae 58 Bronzite 1 MgO:o.11 FeO 
fee aaa 58¢ Diopside 1 MgO:o0.14 FeO 
a ML ah ce Bronzite t MgO:0.10 FeO 
60¢ Diopside t MgO:o0.16 FeO 
| Kappenstein. . . {559 ee t MgO:0.14 FeO 
( 55¢ Diopside 1 MgO:o0.18 FeO 
‘ 49) Bronzite 1 MgO:o. 20 FeO 
WiebSteritie td se ininicr ccceee one ee re Rs 1 MeOro. 46 eG 
ie 50) Bronzite 1 MgO:o. 20 FeO 
Pikrites ec eat tegen tance eee nee 1 MgO:.22 He@ 
: 510 Hypersthene 1 MgO:0.40 FeO 
Hypersthene Diabase.........:-.. Ba ; eie 1 MeOrelee FeO 
If we deduct the small, analytically found figures for Fe,O, from 
the last rock (No. 51), we have: 
Hypersthene, No. 510, 1 MgO: 0.39 FeO; 
Augite, No. 51¢, 1 MgO: 0.35 FeO. 
The seven double analyses of orthorhombic and monoclinic 
pyroxene give approximately the same proportions between MgO 
and FeO, in some cases a little difference in one, and in some in the 
other direction, but there is no:particularly constant enrichment 
of one component in either of the two minerals. A series of analyses 
shows that where orthorhombic and monoclinic pyroxene appear 
as primary formations in the same rock, the monoclinic is charac- 
terized by a somewhat higher percentage of TiO., Cr,O;, ALO; 
—and probably also of Fe,O;—than the orthorhombic. 
DIALLAGE AND PRIMARY BROWN HORNBLENDE 
Kiichler’s two analyses from a diallage-hornblende gabbro 
(No. 52) show, the total quantity of iron being reckoned as FeO: 
Diallage, No. 52c, 1 MgO: 0.57 FeO; 
Hornblende, No. 52d, 1 MgO: 0.48 FeO. 
