RoGeErs. | Minerals of the Galena-Joplin Dvstrict. 459 
Botryoidal sphalerite of a dark brown color constitutes the 
ore at the Spring River Mining Company’s mine west of 
Galena. The stalactitic and botryoidal zinc sulphide from 
Joplin may be wurtzite, as is shown in the description of that 
mineral. 
The color of the sphalerite varies from a light yellow to 
black, through the various shades of red and brown. A green 
color is occasionally seen. Several of these colors are often 
observed in the same crystal or cleavage fragment. A soft, 
white amorphous zinc sulphide occurs on the Moll tract, 
Galena, and near Joplin. This material has been described 
by Mr. Robertson.’ The analysis by the St. Louis Sampling 
Works is as follows: 
Insoluble matter........... 2252 
Tigers rt eee a ee Te sar 63.70 
Seapets rer iratel ME Con to ca h eS 30.77 
Herrickoxiden aaa eee oe 2.40 
AO Galle ear tiwek come eve 99.39 
Most of the sphalerite contains a small percentage of 
iron which is supposed to exist as the isomorphous ferrous 
sulphide. 
An analysis of the dark brown sphalerite from the Spring 
river mines was made by Mr. Edgar Bb. Hayes, with the fol- 
lowing results (the average of two analyses) : 
SiO a ecne oremanteieraiel ie lie enn .28 
1 Raya isos ra se 1.45 
TD Re Ne) ie See er RR 64.20 
Seremban eee a ae ie woke ae aed S318 
MO tal Maun centennial: 99.06 
Covellite. 
Composition, cupric sulphide, CuS; copper=66-4%, sulphur=33-6%; 
hardness, 1-5-2; gravity, 4-590; color, indigo blue or darker; crystallization, 
hexagonal or rhombohedral system; cleavage, basal, perfect. 
Sphalerite from the Big Coon mine on West Seventh 
street in Galena, is often coated with a bluish-black substance 
which penetrates the cleavage surfaces for a considerable dis- 
tance, or, perhaps, as often is entirely replaced by it in the 
form of a soft material of submetallic luster of the same color. 
This mineral has been identified as covellite. We, therefore, 
7. T. D. Robertson: On a New Variety of Zine Sulphide, Amer. Jour. Sci., vol. 40 (3), pp. 
160, 161, 1890. 
