83 
M,— Gold and silver ore from the State of Washington and 
other American localities. 
]Sr. — Zinc-lead ore, Laurium, Greece. 
O. — Copper-silver ore, Leadville, Colorado. Assays gold, $6 
per ton; silver, 41 oz. per ton; copper, 18 per cent. 
P. — Silver-lead ores. Barrier Range, New South Wales. 
Assays silver, 58 oz. per ton; lead, 72 per cent. 
Q. — Gold-copper silver ore, Ouray County, Colorado. Assays 
copper, 28 per cent.; silver, 160 oz.per ton. 
K. — Auriferous quartz, San Miguel County, Colorado. Assays 
average $6 to $S gold per ton. 
S. — Silver and gold ore from the State of Washington, and 
other specimens from American localities. 
T. — Block of ore from 40 foot level of the Back Creek Silver 
and Gold Mine, New South Wales, 36 tons yielded 3,406 oz. silver, 
and gold at the rate of 15 dwt. per ton. 
U. — Auriferous Pyrite, Park County, Colo. Assays $25 worth 
of gold per ton. 
Around the walls of the room will be found, arranged in order, 
large blocks of gold, silver and lead ores, giving an excellent 
opportunity to study the characteristic appearances of such ores 
and the minerals most commonly associated together in them. 
The latter are quartz, fluorite and barite, copper and iron pyrites 
and galena. The rusty looking ores are simply more or less de- 
composed forms of the above. 
HALLS 73, 74 AND 75. 
Hall 73. — Office of the Department of Geology. 
Hall 74. — Library of the Department of Geology. The 
works in this library treat of geology and kindred subjects, and 
are intended primarily for the use of officers of the Department. 
On application to the Curator, however, opportunity will be given 
to visitors to consult any special work. 
Hall 75.— Laboratory of the Department of Geology. 
