USE OF TERMS FEINT AND CHERT ^ 169 
Lake & Rastall . — Textbook of Geology, 1910, pages 151-152. 
Cherts are said to be chalcedonic silica that occur in limestone, 
as in the Lower Carboniferous rocks of North Devon. Flint is 
“nodular and shapeless masses of black or gray chalcedonic silica 
in chalk.” The author gives a definite distinction 
which, of course, would allow a clear usage. 
/. Le Conte . — Elements of Geology, 5th Edition, 1903, page 
169. 
It is specifically stated that flints are siliceous concretions in 
chalk while in limestone they are called chert. 
C. K. Leith . — An article in “Types of Ore Deposits.” 
“Chert as defined in the textbooks, is an amorphous and hydrous 
variety of quartz, but in the field the term has been generally 
applied to siliceous bands such as those found in limestone, with 
little regard to their microscopic or chemical characteristics. Some 
of the so-called cherts in limestones are very fine-grained or 
amorphous. The cherts of the iron formation are similar in 
every respect to those of the limestones. They show the same 
irregularity of texture, interlocking of quartz grains, and often 
very fine grains. However, it cannot be said that any of the 
so-called chert in the Lake Superior region has been found to be 
truly amorphous and hydrous.” Leith probably had in mind the 
bands of quartz which with their distinct crystalline properties 
should not be called cherts. Among the various sources, however, 
flint and chert appear to be regarded more often as cryptocrystal- 
line than amorphous. Evidently the author would base a defini- 
tion of chert on microscopic and chemical characteristics. 
Sir Chas. Lyell . — Principles of Geology, 11th Edition, 1872. 
Flints may occur either in chalk or limestone while chert is 
only impure flint. 
H. A. Miers . — Mineralogy, 1902, pages 373-381. 
“Under the microscope chalcedony is found to be crystalline, 
consisting of minute fibers, they are therefore quite 
distinct from true quartz, and chalcedony is not, as was formerly 
supposed, merely a massive or micro-crystalline quartz . 
‘Flint’ contains sponge spicules and is of organic origin; it often 
contains crystallized quartz in its cavities. ‘Hornstone’ and ‘chert’ 
are names given to compact flinty varieties of chalcedony ; the latter 
is generally also of organic origin.” He evidently distinguished 
flint and chert on the basis of composition, crystalline properties 
and origin. 
