THE MINING AND QUARRY INDUSTRY I9QI12 2 
On 
point of fusibility and when applied to clay wares as a slip, produces 
a rich, brown glaze. Stoneware clays are shipped in a small way 
from Onondaga county. 
The records for 1912 show that the shipments of crude clay in 
that year amounted to 8583 short tons valued at $18,980. There 
were 5 producers engaged in this business. The corresponding total 
for IQI1I was 14,193 short tons valued at $11,982. The difference 
in value indicated by the totals is accounted for by the varying pro- 
portions of the higher priced clays, slip and fire clays, included in 
the statistics for 1912. 
BMERY 
The emery business, which is confined to a few small operations 
near Peekskill, has not been very active in the last year or two. 
The shipments during 1912, as reported by the companies to whom 
they were made, amounted to 589 short tons, valued at $6479. In 
I9II the shipments were reported as 769 short tons valued at 
$8810, and in earlier years were still larger, reaching as high as 
1500 tons at one time. 
The Peekskill emery is a hard, dense rock of rather variable 
composition and dark gray to black color. It occurs in small lenses, 
bands and irregular masses in the area of basic igneous rocks that 
outcrops south and east of Peekskill. The emery bodies are found 
mainly in the northern section of the area and apparently near the 
contact of the igneous, or Cortlandt, series with the sedimentary 
schists. They represent without much doubt segregations within the 
intrusive mass similar to the titaniferous magnetites that occur 
within the gabbros and anorthosites of the Adirondacks. The 
surrounding sediments may have been absorbed more or less into 
the igneous mass on its way to the surface, thereby contributing 
some of the aluminum which has crystallized out in the form of 
corundum and spinel. The intrusion took place after the deposition 
of the Hudson River strata which are made up largely of argillace- 
ous materials. 
The emery is a mixture of corundum, spinel and magnetite, with 
more or less of the silicate minerals that are found in the wall rocks. 
The proportion of the oxids varies greatly. In some places mag- 
netite constitutes nearly the whole mass and such bodies have been 
worked in the past for their iron, though not with much success. 
Spinel (hercynite) is intimately associated with the magnetite, 
though its presence is seldom to be established without microscopic 
examination, being in finely divided particles scarcely distinguishable 
