COKUNDUM IN UNITED STATES. liS7 
emery of about (> feet. Tliis is tlie most extensive deposit of emerv 
known in this country. 
From the V)eo"innin<>- of niinini»' at (Miestei' up to two years ago the 
deposits there yiehled the hirgest production in the United States. 
Now, howeyer, they are exceeded by those at Peekskill. 
P]mery has also been discoyered in the yicinity of Huntington, 
Mass., but no dey(doj)ment work lias as yet been done. 
NEW YOKK. 
The emery deposits of this State occur associated with the norite 
rocks in Westchester County that ha ye been described on page 41. 
Deposits of magnetite and emery haye been found at a number of 
places 3 to 4 miles southeast of Peekskill. These deposits yary con- 
siderably in character, some being a nearly pure magnetite, others 
containing magnetite and spinel, and still others magnetite, spinel, 
and corundum. Those within a mile north and northeast of Crugers 
Station haye been ^vorked for iron ore, Avhile those Avorked for emery 
are in the southeastern part of Cortlandt Township. The principal 
openings haye been made on a ridge running north from Colabaugh 
Pond, and it is here that the ore has been mined. The iron ore and 
emery aj^peared to be yery rich, but it was found upon examination 
that there Avas present more or less of a dark-green mineral mixed 
with magnetite, and this mineral Avas shoAvn by Williams « to be the 
l)leonaste yariety of spinel. There is also considerable spinel in the 
emery, and eyen Avhen the emery is abundant the ore can not be 
distinguished in the hand specimens from that in which there is 
almost none of tlie spinel. 
At the emery deposits in the southeastern part of Cortlandt Town- 
ship the percentage of corundum yaries considerably at dift'erent 
openings, and it is sometimes obseryed in small 1)1 ue, AYhite, and color- 
less crystals. Associated with most of the corundum there is spinel, 
and much of the ore that has been mined for emery has contained 
little or no corundum and has been made up of magnetite and spinel. 
An ore of this sort would haye most of the requisite properties of a 
true emery except the high degree of hardness due to the corundum ; 
and when made up into a wheel it Avould not haye the cutting effi- 
ciency of a true emery wheel. The spinel, Ayhich is 8 in hardness 
(corundum being 9), would play the same part in this ore as corun- 
dum in the true emery, and although not so hard as corundum it has 
the cutting qualities which AYOuld giye the ore considerable yalue as 
an abrasiye. For many purposes wheels made from this material 
could be used fully as well as emery or corundum Avheels, and for 
some purposes they might be used to better adyantage. The spinel 
"Am. Jour. Sci., M ser., vol. .S.3, 1832, p. 194. 
