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“veins” which skirt along the borders of many of the massive outcrops, 
and (2) in interior ‘ extending from the borders toward the center 
of the peridotite mass. The mode is similar in the pyroxenites and in 
certain amphibolites. In other amphibolites, the corundum is irregularly 
disseminated in grains, plates, and nodular aggregates throughout large 
masses of the rock. Corundiferous pegmatite forms small dikes accom- 
panying and penetrating both peridotites and amphibolites in some locali- 
ties. ‘The corundum-bearing serpentines, amphibolites, and _ chlorite- 
schists are simply derivatives of the foregoing types, with more or less 
dynamic and chemical alteration and rearrangement. Corundum-bearing 
gneisses and mica schists, which sometimes pass into quartz-schists, have 
no relation with the peridotites, although occurring in the same region 
and sometimes near the outcrops of these rocks. The chief localities 
of corundiferous peridotites, gneisses, and schists are in Clay, Macon, 
and Jackson Counties, North Carolina, near the southwestern corner of 
the state. Scattering occurrences in amphibolites and gneisses are also 
found east of the mountains, particularly in Iredell County. 
The distribution of corundum is considered in chapter viii. First the 
Appalachian localities are described, including Alabama, Georgia, South 
Carolina, North Carolina, Virginia, Pennsylvania, New Jersey, New York, 
Connecticut, and Massachusetts. Occurrences in Montana, Colorado, 
and California are also described, as well as the corundum and emery 
deposits of Canada, India, Turkey, and the Grecian islands. North 
Carolina localities are described in detail, by counties. 
The alterations of corundum and the minerals associated with it are 
described in chapter ix. The list of associated minerals from North 
Carolina localities includes 62 species, each of which is described, with 
its mode of occurrence and its relations to the corundum. Chemical analy- 
ses and crystallographic characters of many are also given. From other 
American and foreign localities the number of associated minerals is 
increased to seventy-four. 
The origin of corundum is considered in chapter x. The discussion is 
prefaced by an account of the artificial production of the mineral and a 
summary of the various hypotheses that have been advanced during the 
last twenty-five years. From a consideration of field relations and the 
later experiments with silicate magmas, the conclusion is reached that 
the corundum of the peridotites was held in solution in the magma when 
it was injected into the gneisses, and that it crystallized out among the 
first minerals formed, as the mass began to solidify. Corundum in quart- 
schists and gneisses, on the other hand, is the result of metamorphism of 
‘veins,”’ 
