56 
DEPOSITS OF PHOSPHATE OF LIME. 
[BULL. 4G. 
trips a week, carrying 40 to 50 cwt. each trip. This, with the expense 
of getting it to Lisbon and thence to England, makes it cost about $15 
a ton to land in London. First-class phosphorite (80 to 85 per cent.) 
sold there, in 1875, for $25 a ton. 
In the Caceres district, which supplies most of the phosphorite 
shipped from Spain, the mode of its occurrence differs from that in the 
Logrosan district. While in the latter it occurs in veins, sometimes 
of considerable length/ at Caceres it occurs in pockets in great veins of 
quartz and dark limestone, which are found cutting through the coun- 
try slate. The principal mines are united in the Fraterjidad Company, 
and are known as the Esmeralda, Estrella, San Eugenio, Abundancia, 
Cacerefia, San Salvador, and La Peria. 1 The first four, being the only 
mines of much importance, will alone be described. As will be seen 
from the ground plan (Fig. 25), the limestone and quartz veins, in 
which the phosphate is found, occur in both the granite and the slate 
rocks. 
Fig. 25. Ground plan of the Caceres mines in 1875; after Dr. C. U. Shepard, jr. (MS.). 1, Abundan- 
cia mine; 2, Carcereiia mine; 3, San Eugenio mine; 4, San Salvador mine; 5, Estrella mine; 6, Es- 
meralda mine ; 7, La Perla mine. 
The Esmeralda mine is considered the largest and best of the Caceres 
mines. There are two veins penetrating the side of a hill in a north 
1 C. U. Shepard, jr., MS. 
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