CORUNDUM IN ALLUVIAL DEPOSITS EMEHY. T)! 
extensive occurrences of large irregular masses of emery in the white 
crystalline limestone of the province of Aidin, in Asiatic Turkey, 
are well known. 
CORUNDUM IN ALLUVIAL DEPOSITS. 
The gem varieties of corundum are found chiefly in the soil and iu 
gravel beds, as those of Burma, Ceylon, Siam, and other regions of 
southern Asia; the saphire deposits of Lewis and Clark, (iranite, 
and Deerlodge counties, Mont., and the ruby deposits of Macon 
County, N. C. Together with these are also found the connnoner 
varieties of crystallized corunduuL In some of these localities the 
mineral has been traced to its origin in the crystalline rocks. 
The gravel beds re])resent the result of ages of concentration. 
During the time that the rocks were slowly decomposing and crum- 
bling away through the agencies of air and water, the stream beds 
furnished a natural system of sluices, in which the heavy and more 
resistant minerals were caught and retained, while the lighter mate- 
rials were carried farther down the valley. Thus, if all the material 
transported by the streams had been of about the same degree of 
fineness, there would have been an almost perfect deposition of the 
different minerals according to their specific gravity, the heavier ones 
being clei^ositecl higher up the stream and nearer their origin; or, if 
the materials transported had been of various degrees of coarseness, 
but about the same specific gravity, there would have also been an 
almost perfect sorting of the materials according to sizes, the coarsest 
farthest up the stream. Since both of these kinds of deposition 
have been going on at the same time, the heavy minerals and the 
bowlders and large fragments of the lighter ones are found inter- 
mingled, thus forming the alluvial gravel deposits as they are seen at 
the present time. (See PI. IV, yi.) 
Although the corundum gems may have been quite rare in the 
original rock, they have been concentrated in these gravel deposits, 
and are thus found in comparative abundance. Even after the 
corundum of the gravel deposits has been traced to its original source 
in the rocks, the gravels often still remain the principal commercial 
source of the gems. 
EMERY IN UNDETERMINED ASSOCIATION. 
In 1852 Dr. C. D. Hunter « observed masses of emery associated 
with crystalline corundum in granular qiuirtz-mica aggregates at 
Crowders Mountain, in Gaston County, N. C. ; in 1875 Dr. F. A. 
Genth ^ described emery associated with the titaniferous iron ores 
«Am. Jour. Sci., 2d ser., vol. 15, 1853, pp. 873-378. 
^ Rept. Geol. Survey North Carolina, 1875, p. 246. 
