272 
Phase 
Soda microcline.... 
Oligoclase......... 
Soda microcline.... 
Oligoclase......... 
Classification: 
HAROLD L. ALLING 
QUANTITATIVE MICROSCOPIC ANALYSIS 
Percentage K-feldspar ‘ Na-feldspar Ca-feldspar 
69.6 80 18 2.) Ol Ae 
30.4 3 85 12° 
Pistepatehatenci ane 55-6 12.6 I.4 £ oh soe 
Pe tere et ae Ae) 25.9 3.6 2 bis soneleretae 
a uiraiie heel 56.5 38.5 5.0 100 
Popular: Microcline microperthite. 
Technical: Microcline hypoperthite. 
14. “Oligoclase,” Eganville, Ontario, Canada. Specimen 962.) 
Microscopic examination, thin section: The specimen has been incorrectly 
There is some 
oligoclase in the specimen but it is intergrown with soda microcline. 
identified; it is a microcline microperthite—not oligoclase. 
Besides the feldspar phases, biotite and quartz are present. 
Extinction angles, crushed fragments: 
Potashyphases eee. (10) eee ERIS). = 
(Conch eae 18 .0° 
Soda phases ise (Gro) axermenee Seon 
(Gon) hb e hone To0 
LEGS Me cee Ver (OO) ie ween nee SOM 
Index of refraction, soda phase, beta, 1.546 
Inferred Composition Potash Phase | Soda Phase 
K-feldspar........... 70 8 
Na-feldspar.......... 28 75 
Ca-feldspar.......... 2 07 
QUANTITATIVE MICROSCOPIC ANALYSIS 
Phase Percentage Na-feldspar K-feldspar Ca-feldspar 
Soda microcline.... 62 70 28 2). | | Ree 
Oligoclases.. 24... 38 8 75 iy! | ae 
Sodaymicroclines| seers 44.4 7 6 Ti2) | lint eee 
Oligoclase sty 5. ew alice Bef 27.4 6.5: |. kee 
APO tal Sie se aie Nee 47.6 44.7 7.7 100.0 
Classification: 
Popular: Microcline microperthite. 
Technical: Microcline hypoperthite. 
