24 BULLETIN 122, TT. S. DEPARTMENT OE AGRICULTURE, 
(26) PEXX SILT LOAM, SUBSOIL. 
No. 4 sand. — Minerals other than quartz. 14 per cent. Potash feld- 
spars (orthoclase), 5 per cent. Muscovite, 7 per cent. Magnetite- 
biotite, rutile inclosed in quartz, apatite inclosed in quartz, and albite- 
oligoclase are also present. 
No. 5 sand. — Minerals other than quartz. 15 per cent. Potash 
feldspars (orthoclase), 4 per cent. Muscovite. 6 per cent. Mag- 
netite, biotite. tourmaline, oligoclase. zircon, epidote. hypersthene, 
labradorite, and hornblende are also present. 
Silt. — Minerals other than quartz. 40 per cent. Potash feldspars 
(orthoclase) . 4 per cent. Muscovite. 15 per cent. Tourmaline, 
biotite, epidote. hornblende, albite. and augite are also present. 
DISCUSSION OF THE MLNERALOGICAL DATA. 
The general results of the mineralogical examinations support the 
conclusions already given by McCaughey and Fry. 1 The soils of the 
Limestone Valley and Upland province are unique in containing 
quartz crystals with inclusions of caleite and iron oxide. In general 
soils of the glaciated areas are higher in minerals other than quartz 
than soils of the other areas. 
Apatite is reported in 11 out of the 26 samples. The average of the 
phosphoric-acid content of the soils is 0.11 P 2 5 . whereas the average 
of those in which apatite was not recognized is 0.15 per cent. This 
indicates either that the phosphoric acid (P 2 5 N ) of soils occurs in other 
minerals either as a characteristic part or accidentally, or that a large 
part of the apatite is in the clay group, and thus escapes detection. 
Types in which the titanium was larger or of about the same amount 
in the surface as compared to the subsoil contained rutile or rutile 
inclusions in quartz. The percentage of minerals other than quartz 
is higher in the finer separates, and particularly is this true in soils 
of the Piedmont Plateau province. The amount of minerals other 
than quartz is greater in the subsoil than in the surface soil, for the 
respective separates. 
Tourmaline is present in the particles coarser than clay in 18 sam- 
ples. This mineral is particularly interesting for it carries boron as 
an essential constituent. In some cases tourmaline occurs in rela- 
tively large amounts, indicating the presence of boron in more than 
mere traces. The micas, generally muscovite, occur in 24 samples. 
Phlogopite, of which fluorine is an essential constituent, occurs in 
soils Xos. 10, 11. and 12. Fluorine occurs in all micas in amounts 
varying from traces to several per cent, and therefore we would 
expect these soils to contain fluorine 
The amounts of potash feldspars and micas .in various soils have been 
determined by McCaughey and Fry, and is given in Tables III and IV. 
1 Bull. 91, Bureau of Soils, U. S. Dept. Agriculture (1913). 
