= , 
PRISMATIC CRYSTALS OF MEMATITE FROM GUANAJUATO | 138 
by 6. W, MoKee, A 
(From American Journal of Science, March 1904). 
The common forms for hematite crystals are rhombohedra and sca- 
lenohedra. Prismatic faces are seldom well developed. The basal pinacoid 
de is still rarer. Specimens of well erystallized hematite showing crystals of 
am unusual habit were obtained recently from Dr. A. E. Foote, Philadel- 
-—— phia. These specimens are reported to be from Guanajuato, Mexico. The 
A erystals which are very small. seldom more than a millimeter in diameter, 
are well formed and possess a bright metellic lustre such as is character 
-—istic of the specimens from Elba. They oceur spread in a layer over the 
surface of a much decomposed rock, which is probably a rhyolite. 
A A 
da a 
A > > 
A few of the best crystals were selected for measurement on a 
Ñ Goldschmidt two-circle reflecting goniometer. Somo of them showed 
combinations of the prism (1010) and base (0001), while others presented 
in addition to these forms several pyramids of the second order. In all 
cases, however, the most prominent forms were the prism (1010) and the 
base (0001). These faces ordinarily play a very subordinate part in the 
y erystallization of hematite and by their prominence here we obtain a dis- 
tinct prismatic crystal habit hitherto rarely recorded for hematite. The 
