170 
IOWA ACADEMY OF SCIENCE Voi,. XXVII, 1920 
Moses & Parsons . — Mineralogy, Crystallography and Blowpipe 
Analysis, 1904. 
Flint is put under the jasper varieties of quartz. Flint is 
“smoky-gray to nearly black, translucent nodules, found in chalk 
beds.'’ 
William H. Norton . — Elements of Geology, 1905, pages 18, 375. 
Chert is not mentioned. In referring to the limestone of Mis- 
souri it is said to contain nodules of flint that are left on the sur- 
face by the decay and removal of limestone. Further on it is 
remarked that flints were formed in the accumulation of the 
Cretaceous chalk of England and France. Evidently flint is an 
ordinary feature of both chalk or limestone and is not to be de- 
fined on the basis of occurrence alone. 
James Park . — Textbook of Geology, 1914. 
Flints are said to occur in chalk and cherts in limestone. 
A. H. Phillips . — Mineralogy, 1912, page 361. 
“When dark in color and associated with limestone in nodules 
it (chalcedony) forms flint.” There is no mention of chert. 
Pirsson & Schuchert . — A Textbook of Geology, 1915. 
On page 496 an attempt is made to assign separate origins to 
flint and chert but at the end an appended reservation concedes 
that they may be formed in either way. The authors state it has 
been held that flints are of diagenetic origin and the cherts “de- 
velop near the surface in the zone of circulating ground waters 
during the process of weathering.” It is probable also that flints 
are caused by meteoric water. As to definitions. “Flint (p. 274) 
is a dark gray to black, very hard and compact substance occurring 
in irregular nodules, or concretions, in chalk. It is composed of 
silica, Si02, with a little chemically combined water. An impure 
flint, occurring in a similar way, in limestones, is known as 
chert .” In the appendix, page 410, flint “is an intimate 
microscopic mixture of crystallized silica, SiOg (quartz), and non- 
crystalline silica containing some combined water (opal). Its 
color is dark gray, or black, from organic matter ; its hardness is 
well known and like that of quartz ; it cannot be scratched by the 
knife or by feldspar . Its occurrence as concretions and 
masses in chalks and limestones (in the latter often called chert) 
has been alluded to in this book (page 274).” The quotations 
speak for themselves. However, the authors do present a possi- 
ble solution for the lack of a definite term for the great amounts 
of silica interbedded with iron ore. “Somewhat similar masses 
