416 RESEARCH IN CHINA. 
in the gneiss is suggestive of a series of limestone layers, but speculation on 
the subject can not be fruitful without additional facts. 
Gray biotite-hornblende schist, No. 76.—In layers and lenticular bodies 
associated with the gneisses below Féu-p’ing. Specimen taken from the 
side of the river-road 2 miles, 3 kilometers, below the city. 
A gray imperfectly cleaved schist in which black and white minerals 
produce a minutely speckled appearance which is uniform throughout 
the rock. The constituents are chiefly feldspar, quartz, hornblende, and 
biotite, with malacolite (?), epidote, pyrite, magnetite, and tourmaline. 
Orthoclase is the dominant feldspar, with oligoclase in minor quantity. 
The fresh brown to olive-green hornblende appears in irregular bodies inter- 
grown with the paler components of the rock. Biotite is less abundant, 
but is conspicuous in the hand-specimen. The flakes are not aggregated 
in seams, as they are in many schists, but are distributed evenly through- 
out the mass. 
In many respects the schist resembles the amphibolite (75) with which 
it is associated in the field. It contains more feldspars and biotite, and the 
feldspars are alkaline rather than calcic; but otherwise the relationships 
are close. 
ROCKS OF SEDIMENTARY ORIGIN. 
White quartz-muscovite schist, No. 72.—This silvery quartz schist was 
observed only on the northeastern slope of the hill 2 miles, 3 kilometers, 
west of Chuang-li (atlas sheet GI). There it is interbedded with white 
micaceous marble, brown biotite gneiss, etc. The marble is not represented 
in our collection, but its origin is undoubtedly sedimentary; and the schist 
is so intimately associated with the marble that we believe it had a similar 
origin. 
A gray-white rock composed of translucent granular quartz, white 
muscovite, and a little orthoclase. The parallel arrangement of these 
minerals imparts a fairly good cleavage. 
The complete recrystallization of the mass has obliterated its former 
constituents and structures. The changes which occur in rocks during 
metamorphism are still too imperfectly understood to enable us to deter- 
mine the ancestral character of this schist. In the field relation, however, 
it occurred in seams between beds of marble as if it represented shale bands 
in the original limestone. If it has been produced from a shale, we must 
admit that profound chemical changes have taken place, resulting in an 
increase in quartz and a decrease in the alumina, lime, and magnesium. 
Changes of this magnitude are known to occur abundantly in the zone of 
anamorphism. 
