Naming Rocks. 157 
the feldspar. It is generally associated with archen 
rocks (metamorphic). | , 
Chlorite-schist—A nother metamorphic rock, consist- 
ing of a foliated arrangement of quartz and chlorite, con- 
taining also magnitite and mica. This rock is greenish 
in color and has a greasy feel. It is generally associated 
with gneiss. 
Hornblende-Schist—A foliated arrangement of 
quartz and hornblende, sometimes with orthoclase. It is 
dark-greenish in color, and is a schistose structure of 
amphibole or massive hornblende. 
Talcose-schist—An arrangement of quartz and tale 
in layers. It is light-green in color, very greasy to the 
touch, and occurs only in isolated beds. Metamorphic. 
Hydromica-schist—Commonly called talcose-schist. 
It is a choritic-mica schist with water. 
Soapstone or Steatyte—A highly compressed, schist- 
ose, massive tale, often impure; color, grayish-green, 
gray and white. Easily cuts with a knife. Metamorphic. 
Serpentine—A yellow, greenish-yellow, or green 
mottled rock, greasy to the touch and easily scratched 
with a knife. It is a result of the decomposition of 
olivine-bearing schists, the silicate of magnesia contained 
in the olivine rock having become hydrated (i. ¢., wa- 
tered or moistened). Metamorphic. 
STRATIFIED, SEDIMENTARY, OR AQUEOUS ROCKS. 
Silt—A fine sediment which gathers in quiet waters, 
in hollow places of rivers, lakes, estuaries and seas. 
Alluvium, Silt, Till—Alluvium is the earthy de- 
posit made by running streams or lakes, especially dur- 
