44 
201. PHOTOGRAPHS of Rosolite Quarry, Xalostoc, Mexico. 
202. GADOLINITE (basic ortho silicate of yttrium, beryllium, and 
iron). The largest crystal of this rare mineral ever found. 
Dimensions, II in.x 6 in. Weight, 184 lbs. Found at Bar- 
ringer Hill, Llano Co., Texas. 
203. YTTRIALITE (silicate of yttrium and thorium). Barringer 
Hill, Llano Co., Texas. 
204. THOROGUMMITE (a hydrous silico-uranate of thorium). Bar- 
ringer Hill, Llano Co., Texas. 
205. NIVENITE (a hydrated uranium-thorium-yttrium-lead uran- 
ate). Barringer Hill, Llano Co., Texas. 
Note.—From the three last named minerals thoria is ex- 
tracted, the principal element in the manufacture of the 
Welsbach lamp. 
Nos. 200-205 exhibited by William Niven. 
206. QUARTZ CRYSTAL showing the tetartohedral form of the 
pyramid of the second order, the trigonal pyramid. Crystal 
Peak, Colorado. 
207. QUARTZ CRYSTAL. Example of fine etching. Lincoln Co., 
North Carolina. 
208. QUARTZ CRYSTAL. Amethystine, highly modified. From 
a new locality in Lincoln Co., North Carolina. 
209. QUARTZ CRYSTAL. Of cubic aspect; the plus rhombohedron 
predominating and the minus rhombohedron and the prism 
being greatly reduced. San Miguel Co., New Mexico. 
210. RHODOCHROASITE AND RHODOCHROSITE GEM. Clima, 
Colorado. 
211. MICROCLINE. A group of nine basal twins. Crystal Peak, 
Colorado. 
Nos. 206-211 exhibited by Lazard Cohn. 
212. OPAL. Two examples of opal infiltrations in a jasperoid iron- 
stone. Baricoo, New Zealand. These opal films occur ina 
concretionary ferruginous sandstone or jasper, and have been 
formed by the deposition of opal silica through the crevices 
of the enclosing ironstone. 
