DEPARTMENT OF GEOLOGY 
35 
beryl, a mass of lapis-lazuli weighing about 200 pounds, a 
splendid group of epidote from Alaska, and large and fine speci- 
mens of tourmaline. Passing to Hall 64, the first wall case at 
the left contains a complete series of the varieties of mica, fol- 
lowing which are the hydrous micas, the serpentines, talcs and 
clays, and the minerals containing the rarer elements, such as col- 
umbite, samarskite, etc. Following these in the wall cases on the 
north side of the hall are the phosphates, arsenates, borates, 
uranates and sulphates. Among these the vanadinites from 
Arizona, and olivenites, conichalcites and tyrolites from Utah, 
are of exceptional beauty and rarity. The turquoises from Ari- 
zona, autunites from South Dakota, barites from England and 
anglesites from Utah are also noteworthy. The systematic 
collection terminates in the wall cases on the east wall in the last 
case, especially noteworthy being the specimens of wulfenite 
from Arizona, amber from Prussia and jet from England. A 
collection of pseudomorphs illustrating how one mineral may be 
replaced by another follows. Then is exhibited a collection of 
radio-active minerals with photographs made by the specimens 
themselves. Large gold nuggets found in Australia and Cali- 
fornia are next represented by full-sized models. In the floor 
cases of the hall several hundred specimens of cut gems and 
ornamental stones are shown. These include topazes, ame- 
thysts, emeralds, tourmalines, moonstones, rock crystal, amber, 
etc. The specimen of carved amber is especially remarkable as 
a piece of lapidist work. The series also includes a number of 
jasper vases and trays from the Urals and pieces of polished 
serpentine and onyx. A complete series of models of the famous 
diamonds of the world, illustrating their size, form, and color, 
makes a part of the exhibit. The Chalmers crystal collection, 
which includes about 250 specimens 'from United States localities 
and is the most complete collection of the kind ever made, occu- 
pies one case. 
Hall 65. 
STRUCTURAL and DYNAMICAL GEOLOGY. 
The specimens in this hall for the most part represent phe- 
nomena met with in the study of the earth’s crust, and illustrate 
phases of rock structure and geological processes. Entering 
from Hall 64, in the first case at the left are shown large slabs 
with ripple-marked surfaces. One of the largest of these shows 
