Oligoclase 
Microscopic examination. 
really a microcline microperthite with some accessory quartz. 
Extinction angles, crushed fragments: 
Potash phase 
Soda phase 
Inferred Composition 
K-feldspar 
Na-feldspar 
Ca-feldspar 
eee ee ee eo oe 
ee ee © © © 
Potash Phase 
22 2 eo © © © ew © oo 
oe © ee © et ew 
eee coo 
ec eee 
Soda Phase 
2 
80 
18 
QUANTITATIVE MICROSCOPIC ANALYSIS 
Phase 
Soda microcline. . . 
Soda microcline. . . 
Percentage 
eee ee eee ee ee oe 
Classification: 
K-feldspar 
Popular: Microcline microperthite. 
- Technical: Microcline hypoperthite. 
Na-feldspar 
25 
80 
THE MINERALOGRAPHY OF THE FELDSPARS 269 
QUANTITATIVE MICROSCOPIC ANALYSIS 
Phase Bhasen pecan ii maecen di dase base K-feld. | Na-feld.| Ca-feld.| Fe.O; 
80 fo3.5 | Soda micro. | 80 17 3} GENE 
Perthite {K-feld. | 6.5 | Albite 2 2 07 I feawl| eowsrcsiece 
ea \Na-feld. | 19.5 |(19.5 | Albite 1 2 07 Te) eet ees 
Hematite... .|........-- AS eeaes voce teva eauetcaerrenel eal Mrchaeaua lfareamvtictet| tdi dc 100 
89 ((Sodapnni cromeams5Onon en 2e7) lez)? lll eseiers 
Perthit {Ka-feld. | Albite 2 st || Soi HUlf|steciage 
Bees \Na-feld. 19.5 (Albite x || 23. Pinan eee 
HVE MA LILES sralol-) << aisiers o ose sltsot i ott| leah pen ENGas Cecchi oeen cuca | ai a EUG aden rit 25 
Roe Stare are ces cial eeeoucncnecaeacusied leet esroimaialemtes 60.3 | 36.7 2 55 55 
Classification: 
Popular: Microcline microperthite 
Technical: Microcline hypoperthite. 
10. ““Microcline,’’ Verona, Ontario, Canada. (Specimen 950.) 
The microscope shows that the specimen is 
Ca-feldspar 
