26 
sandstone of greenish-gray color. The grains of quartz vary 
from .08 to .o1 of a millimeter in diameter and many give polor- 
ization colors of a high order. The silica is imbedded in a matrix 
of calcareous earth containing a large percentage of iron, and 
there are present also flakes of muscovite, sometimes bent be- 
tween the grains of silica. The iron is limonite unevenly distrib- 
uted, which binds the particles of the stone together by its 
branching lines. The aggregation of iron into these lines repre- 
sents probably a secondary process, but with the exception of this 
and some doubtful secondary quartz, the stone is an unaltered 
sediment. Considerable effervesence occurs when treated with 
dilute hydrochloric acid. The abrasive qualities are due entirely 
to the rough quartz grains.” 
This description emphasizes the fact that the Labrador stone 
is a strong slowly wearing stone with a grit of medium fineness. 
Its strength and resistance to wear being its important qualities. 
It is well adapted for kitchen stones into which it is manufac- 
tured in considerable quantities. In this respect it differs from 
both of the other fine grained sandstones, which are not strong 
enough for kitchen stones or files. The Hindostan is better fitted 
for the ordinary tools of carpenters and mechanics, while the 
Adamascobite is too soft and too expensive for an economical 
carpenter’s stone. The Labrador stone, on the other hand, is 
not only a good but at the same time a handsome stone for all 
kitchen and table purposes, also for the various forms of files, 
and in fact for all whetstones where the tools permit of a consid- 
erable pressure, and do not require an extremely fine edge. It 
makes a first-class intermediate stone to use before finishing on 
the Arkansas. In speaking of its peculiar adaptation for kitchen 
purposes, a recent catalogue of the Pike Company says: “ It is 
a handsome stone cut from a solid piece of Labrador rock. It 
has a sharp, medium coarse grit, and gives a splendid edge to 
carving knives. It is strong and more desirable for ordinary 
kitchen or table use than the emery, as it will not glaze, nor eas- 
ily break.” 
MaNvuFacturRE. ‘The preparation of whetstones for use 
has always been a simple matter; the principle being the same for 
