Rogers. | Minerals of the Galena-Joplin District. 497 
Kaolinite. 
This mineral was observed as a thin, white coating on the 
micaceous shale at Cave Springs. It was also found in cavi- 
ties in chert at the Tree Toad mine, northeast of Galena. 
Allophane. 
A hydrous aluminum silicate related to allophane in com- 
position occurs at the Big Coon mine, and at the mine of the 
Dearborn Mining Company, at Galena. ‘The mineral appears 
as a thin incrustation, often with a botryoidal surface, asso- 
ciated with sphalerite, chert, and a soft, clay-like material. 
It is amorphous, colorless to light brown or green, subtrans- 
lucent, with a resinous luster, and has very much the appear- 
ance of gum arabic. In physical characters it agrees very 
well with the description of schrotterite, but is quite differ- 
ent in chemical composition. Mr. C. A. Wolfaith, superin- 
tendent of the Dearborn mine, kindly furnished the material 
for analysis. An incomplete analysis gave the following, 
which is a mean of two determinations: A1I,O,, 41.66; SiO,, 
24.76; H,O, 33.48 ; total, 100.00. Specific gravity,1.94. The 
silica percentage is rather high and that of the water rather 
low for allophane, but is much nearer that mineral than any 
other, and so is referred to it. 
Recently the writer has found allophane of the light 
greenish-bluish color so common in this mineral at the Irene 
mine, Empire, Kan. 
Chrysocolla. 
Chrysocolla occurs as thin seams of bluish-green color as- 
sociated with other copper minerals at the Big Coon mine, 
Galena. 
Pyromorphite. 
Observed forms: 0/0001) Op; a(1010) @P. 
The crystals are usually very small, though they are some- 
times as much as a centimeter in length. The forms present 
on most of the crystals are the unit prism and basal plane. 
On some from ashaft west of the Black hill, on the Schermer- 
horn ground, west of Galena, a steep pyramid whose symbol 
could:not be determined occurs. 
