466 University Geological Survey of Kansas. 
and Wentworth crystals were found which measure 2} cm. 
in the direction of the vertical axis, but such are very rare. 
The absence of large quantities of crystallized quartz has an 
important bearing upon the origin of the ores, as has been 
brought out in the chapters on the geology of the district. 
The massive quartz of the region, commonly known as flint 
or chert, is of the two kinds, primary and secondary. The 
latter Jenney has called ‘‘cherokite,’’ because of its abun- 
dance in and about Galena, which is located in Cherokee 
county, Kansas. These two varieties of chert differ in phys- 
ical characters, the one being white or light shades of blue, 
the other black or dark gray. They are closely related in 
chemical composition. 
Cuprite. 
Composition, cuprous oxide, Cu20; copper =88-8%, oxygen =11-2%; 
hardness, 3-5-4; gravity, 5-85-6-15; color, red of various shades; crystal- 
lization, regular system. 
Cuprite was observed as a secondary mineral in a chert 
breccia associated with chalcopyrite, malachite, and other 
copper minerals. It also occurs as a central core surrounded 
by massive malachite, from which the latter was evidently 
formed. The mineral is of the characteristic dark red color. 
It was found only at the Big Coon mine, Galena, which, 
though a very insignificant mine, furnishes a great variety 
of copper minerals. 
Hematite. 
Composition, iron sesquioxide, Fe:03; iron =70 %, oxygen =30 %; hard- 
ness, 5-5-6-5; gravity, 4-9-5-3; color, dark, steel gray, or iron black, in 
very thin particles blood red by transmitted light; crystallization, rhombo- 
hedral system. 
The mineral hematite occurs as a thin, black, botryoidal 
incrustation with a metallic luster in chert cavities at Cooper 
hollow, in the eastern part of Galena. It is frequently ob- 
served as a soft, red stain on rocks in all parts of the district. 
Pyrolusite. 
Composition, manganese dioxide, MnOs; manganese=63-1%, oxygen = 
36:9%; hardness, 2-2-5; gravity, 4-82; color, iron black, dark steel-gray, 
sometimes bluish; crystallization, orthorhombic system. 
A soft, black mineral from a shaft west of Black Hill, in 
