484 GEORGE I. FINLAY 
analyses of kyschtymite falling in the perfelic order Siberare des- 
cribed by the same author. The present occurrence of modal corun- 
dum is one in which the rock is much more siliceous than are the rocks 
above mentioned in the corundum-bearing subclasses of the persa- 
lanes. From a quantitative study of its mineralogy it is placed 
tentatively in the order Columbare of Class I. It is domalkalic. 
Dumortierite is a basic aluminic silicate, AlgSi,O,3, with a part of 
the aluminium replaced by boron. It might reasonably be expected, 
therefore in a siliceous rock rich in alumina, as is the pegmatite vein 
near Canyon City. Dumortierite has been reported from a pegma- 
tite vein in schist at Harlem, N. Y.,! and from Clip, Yuma County, 
Ariz. It has been found in similar occurrences near Lyons, France, 
and near Schmiedeberg, Silesia, as well as in gneiss at Tvestrand, 
Norway. The present occurrence seems to justify the view that for 
it corundum and dumortierite are original pyrogenic accessory con- 
stituents, and that in other igneous rocks these minerals may occasion- 
ally play the same part. 
t For a systematic account of the reported occurrences of dumortierite see W. T, 
Schaller, Bulletin 262, U. S. Geological Survey, p. 91. 
