INORGANIC COMPOSITION OF SOME AMERICAN SOILS. 23 
birefringence of pyrophyllite. They are not to be confused with the 
fibrous variety of epidote which has a much higher refractive index 
and results from the alteration of plagioclase feldspars; chlorite and 
magnetite are also present. 
(22) YORK SILT LOAM, SUBSOIL. 
No. 4 sand. — Minerals other than quartz, 10 per cent. No potash 
feldspars. Muscovite, 2 per cent. Magnetite, biotite, and tour- 
maline present. 
No. 5 sand. — Minerals other than quartz, 12.7 per cent. No potash 
feldspars. Muscovite, 1 per cent. Pyrophyllite present in large 
quantities. Magnetite, chlorite, tourmaline, and epidote also present. 
Silt. — Minerals other than quartz, 85 per cent. Characterized by 
a high muscovite and pyrophyllite content. Rutile present. 
(23) LOUISA LOAM, SOIL. 
No. 5 sand. — Minerals other than quartz, 7.7 per cent. Magnetite, 
zircon, chlorite, muscovite, and apatite inclosed in quartz are present. 
Silt. — Minerals other than quartz, 51 per cent. Potash feldspars, 3 
per cent. Muscovite, 2.3 per cent. Magnetite, biotite, epidote, and 
chlorite predominate; tourmaline, zircon, and rutile are also present. 
(24) LOUISA LOAM, SUBSOIL. 
No. 5 sand. — Minerals other than quartz, 10 per cent. Magnetite, 
zircon, hematite, and apatite inclusions in quartz are present. 
Silt. — Minerals other than quartz, 60 per cent. Potash feldspars 
(orthoclase), 2.5 per cent. Muscovite, 1.7 per cent. Biotite, chlorite, 
orthoclase, and muscovite predominate; epidote, zircon, magnetite 
diallage, and rutile are also present. 
(25) PENN SILT LOAM, SOIL. 
No. 4 sand. — Minerals other than quartz, 10 per cent. Potash 
feldspars (orthoclase), 1 per cent. Muscovite, 6 per cent. Labra- 
dorite, zircon, apatite inclosed in quartz, hornblende, rutile, mag- 
netite, and hematite are also present. 
No. 5 sand. — Minerals other than quartz, 15 per cent. Potash feld- 
spars (orthoclase), 6 per cent. Muscovite, 4 per cent. Magnetite, 
hematite, labradorite, tourmaline, hornblende, andalusite, zircon, 
and albite-oligoclase are also present. 
Silt. — Minerals other than quartz, 18 per cent. Potash feldspars 
(orthoclase), 5 per cent. Muscovite, 9 per cent. Tourmaline, bio- 
tite, epidote, hornblende, albite, apatite, and augite are also present. 
