DEPARTMENT OF GEOLOGY 
53 
lish mines, as do also the specimens of calcite and galena. Some 
of these ores, as for example that of Snail Beach, are from 
mines formerly worked by the Romans. Note the general 
absence of “carbonates,” and the fresh, undecomposed appear- 
ance of the specimens. This is also true of the Spanish and 
German ores. Carbonate and disintegrated ores occur near the 
surface where air and atmospheric waters have acted and 
formed them from the sulphides. These mines having been 
long worked, most of the superficial ores have been removed, 
so that now only the sulphide ores occurring at great depths 
are mined. 
Gold ores from Great Britain are represented by specimens 
from a single Welsh mine. This series from the New Morgan 
mine, Dolgelly, Wales, is worthy of special attention both on 
account of its completeness and of the character of the ore. 
The gold is nearly all free, and much of it is visible to the eye. 
Specimens of ores from various parts of the mine are shown, 
also specimens of the country rock. 
The silver ores of Greece are represented by a unique series 
from Laurium, including slags left by the ancient smelters 
which are now mined and smelted anew. The mines of this 
locality had been operated by the Greeks from before the time 
of Themistocles up to the first century, A. D. Owing to the 
imiperfect methods used, however, the slags produced retained 
appreciable quantities of metal. A modern company, collecting 
these slags and using them as ores, extracts sufficient lead and 
silver to yield a profit. 
A series of lead-silver ores from Germany is especially 
instructive, as it shows the characteristic structure of veins. The 
different minerals are arranged in bands or layers and the metal- 
liferous layers alternate with those of quartz, barite, or fluor- 
spar. 
African localities are represented by the banket of the Trans- 
vaal, and ores from Rhodesia. 
Three rows of table cases run the length of this Hall. They 
contain large specimens of ore which could not well be dis- 
played in the smaller wall cases and a number of special collec- 
tions. 
The large specimens, which include types of all the ordinary 
varieties of gold, silver and lead ore, serve to give a truer idea 
