DEc., 1908. | MINERALOGICAL NOTES | 139 
account of calamine,* of a habit quite similar to the above and 
also from a Maid of Erin mine. The occurrence described by Pratt 
is, however, in Clear Creek Co., Colorado, while the 
locality here represented is in Lake Co. As the crys- 
tals prove upon examination to exhibit a development 
somewhat different from that described by Pratt, 
there seems little doubt that they represent a separate 
occurrence. Inquiry by the writer of the company 
now operating the mine from which the Leadville 
calamine was stated to have come, elicited the infor- 
mation that some of the workmen thought that such 
crystals had been obtained in earlier operations at 
the mine but none was being found at the present 
time. The company also forwarded a specimen quite 
similar to the one above mentioned, with the informa- 
tion that it had been found at the El Paso mine 
adjoining. 
Like the Clear Creek Co. calamine, the Leadville 
crystals are tabular with respect to b (o10) and con- 
siderably striated in the prismatic zone. They are, 
however, differently terminated. Most commonly 
the termination is the unit macrodome s (101). 
Occasionally, however, the steeper dome ¢ (301) is to 
be seen and the unit brachydome probably also occurs although this 
could not be verified. The usual appearance of the crystals is illus- 
-.trated in the accompanying Fig. 1. Occasionally there is a larger 
development of the prism, giving a stouter form. The crystals tend 
to form groups which are partly radiated and partly joined by the 
brachy-pinacoid. No doubly terminated crystals were found, so 
that no opportunity was afforded for a study of the hemimorphic char- 
acters of this mineral. Gentle heating causes the crystals to become 
strongly electric. The character of the electricity developed by such 
heating was tested in the following manner: Numerous crystals were 
suspended by silk threads and after heating, glass rods electrified by 
silk or sealing wax excited by flannel were brought near., In every 
case the positively electrified substance, i. e., the glass, attracted the 
terminated end of the crystal and the negatively electrified, the broken 
end. The average length of the crystals is about 1omm. They are 
transparent to translucent and colorless to white. The faces best 
suited for measurement are the macrodomes, an especially sharp 

Fic. 1. Calamine. 
FOAM JOUTAIOC!., 1804, 3, 40, D- 213. 
