114 ^^^^ American Geologist. August, looi 
iiuilennaiieite ; also the coni])lete scries of uranium minerals 
used in investigations by Hillebrand which led to the discovery 
of nitrogen in nraninite and indirectly to the discovery of ar- 
gon. 
Among the more notable suites in the exhibition series may 
be mentioned a magnificent collection of Copper Queen azur- 
ites, Siberian topazes, and twinned calcites containing arbores- 
cent copper from the Lake Superior region. The collection is 
rich in specimens from the older Pennsylvania localities, as for 
example, a magnificent series of brucites mainly from the collec- 
tions of Isaac Lea and Joseph Leidy ; also a series of zaratites 
on chromite from the old Wood mine, Texas, Lancaster county, 
Pennsylvania. 
Worthy of particular note here is a recent accession from 
Dr. C. U. Shepard of Summerville, South Carolina, compris- 
ing the entire private collection of the late Prof. Chas. U. Shep- 
ard. This is especially valuable, since it contains Dr. Shep- 
ard's type materials and specimens, from which drawings were 
made for purpose of illustration in the earlier works on miner- 
alogy. It also contains fine examples from localities now in- 
accessible or exhausted. 
The large block of native copper described bv Schoolcraft 
in his narrative of explorations of the source of the Mississippi 
in 1820, from Ontonagon county, Michigan, is displayed in this 
section of the department. 
A comparative series, designed primarily for students of 
mineralogy, and which illustrates various characteristics or 
properties of minerals, containing some 2,800 specimens, is ar- 
ranged along the west side of the hall. The gem collection, 
which since the recent generous accessions to the collections in 
the American Museum in New York, now ranks as second of 
the public collections in the country, owes its origin to an ex- 
hibit of precious stones made by the National Museum at the 
Cincinnati and New Orleans expositions in 1884 and 1885. In 
1894 the museum secured by purchase the Leidy collections of 
gems and later, by request, the important collection of Dr. Isaac 
Lea. Since that time the growth has been rapid and system- 
atic, owing largely to the influence of the honarary custodian. 
Dr. L. T. Chamberlain. Particular efifort is made to illustrate 
the gem resources of the L^nited States. A large, rich green, 
