THE MINERALOGRAPHY OF THE FELDSPARS 
Extinction angles, crushed fragments: 
Potash) phase;ass. (Gide) ea a ee 7 Oo 
(Com) Ramee ase 109) Oe 
Sodas phases sere (Chie) anes Raat 115} 
(Com) praia ee TO 
Inferred Composition | Potash Phase Soda Phase 
K-feldspar........... 79.0 2.0 
Na-feldspar.......... 19.0 89.0 
Ca-feldspar.......... 2.0 g.o 
QUANTITATIVE MICROSCOPIC ANALYSIS 
Phase . Percentage K-feldspar Na-feldspar Ca-feldspar 
Soda microcline.... 71.5 79.0 19.0 2.0 
Oligoclase......... 24.1 2.0 89.0 9.0 
CYWBUREZ So 6.6’ ict Bresctesne Oke ie eee RE MESsne | crc tse ei |e Pua Lea ge PE 
Soda microcline....}........... 56.5 13.6 it di, 
PO CIASE! sr cirsce =o se alee tes a5 2A. 242 
Qi. o o'0\d tb Ghats Beal a ecneMnenO ei 6. LOIRE Goto CaniG| | re once coer cers Seana 
MING Gal Desvayerat pete | sichbs. = ae crete 57-0 35.0 3.6 
Classification: 
Popular: Microcline microperthite 
Technical: Microcline hypoperthite 
27% 
Silica 
13. ‘““Microcline Amazonstone,” near Florissant, California. (Specimen 971.) 
Microscopic examination, thin section: Intergrowths of potash and soda 
rich feldspars. Microclinic twinning beautifully shown. 
Extinction angles, crushed fragments: 
Rotash)paasese sae a. (Cro) BB 
(Com) a ee 09/ () 
Sodas phase mmeieus eae (IO) ais oes T2Oy 
(Como ake mini ALOR 
Inferred Composition Potash Phase Soda Phase 
kételdspaipecrm nee : 80 3 
INasteldsparen eee sa. 18 285 
(anteldspakeeneeeinnne 2 12 
