350 The American Geologist. May, 1894 
in English & (Jo's mineral collection also calls for special re- 
mark. 
White mica for commercial purposes was exhibited by the 
Palermo Co., of Groton, N. H., and from the Ray mines in 
North Carolina, while the huge sheets and crystals of phlogo- 
pite (amber mica) from Canada, now in demand for electrical 
apparatus, was quite a novelty. 
Cut and polished agates were shown by Krauth and Dreher, 
of Oberstein, where this industry is principally carried on, 
while the fine Bigelow collection of agates, accompanied by 
many thin sections, was displayed by Harvard University in 
the south gallery of Liberal Arts. 
Meteorites were shown in great number and variety by 
Ward, of Rochester, by Harvard Universit} 7 , and by Mr. G. F. 
Kunz. 
Scattered among the various state buildings were a few 
collections of some interest, while in others specimens of char- 
acteristic crystals were on sale. Thus good crystals of copper 
could be had in the Michigan building, orthoclase in the Col- 
orado building, rubellite and serpentine in the California 
building, Sioux jasper, tin ore and rose quartz in the South 
Dakota building, etc. 
The exhibit of minerals in the Government building was a 
selection from the well-known cases in the National Museum, 
and in its beauty, arrangement and educational value it came 
up to the high standard set by that institution. 
In these notes no attempt has been made to take into con- 
sideration exhibits of ores, metals, coal, oil, clays, asbestos, or 
other minerals of purely commercial interest. 
///. Petrographical Materials and Collect ions. 
These may include abrasives, microscopic rock-sections, sys- 
tematic collections, ornamental stones and building stones : 
but again, no attempt will be made to enumerate any ex- 
hibits which did not have a scientific bearing. To both 
abrasives and building stones a long report might easily be 
exclusively devoted, but they can here be mentioned only in 
so far as they bear on the theoretical aspects of petrography. 
Of much importance to all interested in preparing sections 
of minerals or rocks is the recently discovered abrasive ''car- 
borundum, ,- now manufactured and put on the market in all 
