262 HAROLD L. ALLING 
CHEMICAL AND MICROSCOPIC ANALYSES 
SiO. Al,O; Fe.0; CaO K.0 Na.O Total 
(Amally sister nciie eroen Ono Ae || 2a.9%7 0.36 | 4.78 T26) 8.50 | 100.00 
K-feldspar Na-feldspar Ca-feldspar 
Chemical occas nee 7.45 69.62 22.93 
Mucrascopice sence reo FAO 70.0 23.0 
Classification: Oligoclase. 
Analysis. James D. Dana, System of Mineralogy. Oligoclase and oligoclase- 
albite No. 11. Asch, The Silicates in Chemistry and Commerce. No. 40. Scheerer, 
Poggendorff’s Annalen, 64, 1845, 153. 
(Specimen 967.) 
Microscopic examination, thin section: Normal plagioclase with albite 
twinning. Small inclusions of rutile, ilmenite (?), diopside, and hematite. 
Extinction angles, crushed fragments: 
4. “Labradorite,”’ near Nain, Labrador. 
(010) 20° 
(Con))ys 25 
Maximum, Zone | (010) 33° 
Inferred composition, ignoring potash component: Ab,,Ans¢. 
Inferred composition, considering potash component: 
Kefeldspatan seemer 250 
Na-feldspar....... 44.0 
Ca-feldspar....... 54.0 
CHEMICAL AND MICROSCOPIC ANALYSES 
SiO: Al.O3 CaO Na.O K.0 Ign Fe.0; | MgO Total 
Deer yckaeel FORGOn 27/50 LOmLOn 5 OO PAOy | ated -70 Io 99.80 
De ee reerate ten nraee FOSS || 27oRS || WO88 | S07 £6 Benes 1.38 Aa 100.75 
(ae a eaiale enamine A Sin |i Onl | LOMOOM |G inne 58 .56 269) eee T00.02 
K-feldspar Na-feldspar Ca-feldspar 
Di evvaearsuchaicintens 2.50 44.70 52.41 
Di trsvatalaler gainers 2.21 45.10 52.61 
CTE ICTR GRE ORCE BRS 43.80 Fenon 
Microscopic. . 2.0 44.0 54.0 
Classification: Labradorite. 
Analyses. 
James D. Dana, System of Mineralogy, Labradorite Nos. 23, 24, 25. 
