266 
HAROLD L. ALLING 
QUANTITATIVE MICROSCOPIC ANALYSIS 
Phase Percentage K-feldspar Na-feldspar 
Sodapmicroclinesmeren seer QI 80 18 
Albite-oligoclase........... 9 2 88 
Sodasmicroclineanee renee eee ree TR 16.2 
All bite-olteoclaseiaae renee eee eee see Sit ed] 
TRO tall sta a rdeclts note hoy kevenenoll Cerone rere 73.4 23.9 
Classification: 
Popular: Microcline microperthite 
Technical: Microcline hypoperthite. 
Ca-feldspar 
6. ‘‘Microcline,”’ Etta Mine, one mile south of Keystone, South Dakota. 
(Specimen 965.) 
Microscopic examination, thin section: Microcline microperthite with 
quartz, diopside, sericite, and carbonates. 
growths is oligoclase. + 
Extinction angles, crushed fragments: 
Potashyphasenys..--- (Gro) eee 6.0° 
(Son) isis eRe 17eon 
Sodalphasers qatar (oLo)ee HR 7 O° 
(Con) EME eee Bn Or 
Inferred Composition Potash Phase Soda Phase 
iKketeldspareenneeeeiee 80. 3 
Na-feldspar.......... 17. 80. 
Ca-feldspar.......... Be 17. 
QUANTITATIVE MICROSCOPIC ANALYSIS 
The sodic phase of the inter- 
Phase Percentage K-feldspar Na-feldspar Ca-feldspar 
Soda microcline........... 87.5 80 17 3 
Oligoclase We ean TD, B 80 17 
Sodamicroclinesy aueen eee err ieee 70. 14.9 2.6 
Oligoclase ae wha se vsverses weer eeereece ee redeces ae ag 10.0 2.12 
PLO tall nse Le cee 8 cts te ate etcl leer ream Meyanae ks 7OnG 24.9 4.8 
Classification: 
Popular: Microcline microperthite. 
Technical: Microcline hypoperthite. 
