306 J. D. TRUEMAN 
composition between the schist and the quartzite was not caused 
by the introduction of material from igneous intrusives. 
a) There are no igneous intrusives known to cut the quartzite 
except pegmatite dikes several miles from the outcrops from which 
the samples of quartzite and schist were taken. These dikes do 
not appear to contain either zircon or ilmenite. 
b) Neither zircon nor ilmenite are minerals which are known 
to develop in small grains throughout a contact rock. Neither 
mineral has a freshly crystallized appearance either in the quartzite 
or schist. 
c) There are no minerals in the schist which do not occur to 
some extent in the quartzite. 
The following points seem to show that the sericite schist has 
generally been developed from the normal quartzite by dynamo- 
metamorphism and that during the alteration there has been a 
large loss in material, probably mostly silica: 
a) Both TiO, and ZrO, are distinctly more abundant in the 
schist than in the quartzite. The ratio of the increase in percentage 
is in each case approximately the same. 
b) Warner’s analyses show that the percentage of all other 
constituents except silica is greater in the schist than in the quartz- 
ite and that the ratio of the increase in amount is in each oxide, 
except silica, approximately the same. 
c) Presence of quartz stringers associated with some of the 
bands seems to indicate that quartz was eliminated during the 
formation of the schist. 
On an assumption of such a change in composition, as outlined, 
it is to be supposed that all gradations must exist between the 
normal quartzite and the most highly developed sericite schist. 
This affords a satisfactory explanation why Warner’s figures seem 
to indicate a concentration of as high as 2.6 or even 2.9 while 
the more recent analyses of TiO, and ZrO, only indicate a con- 
centration of about 2. It is to be hoped that a complete analysis 
of the two rocks will some day be available in order, that by com- 
parison with the ZrO, and TiO, it may be possible to obtain more 
definite proof of the relative stabilities of the oxides during the 
alteration. 
