Bulletin of the United States Geological Survey--The Nature and Origin of Deposits of Phosphate and Lime . rips a week, carrying 40 to 50 cwt. each trip. This, with the expenseof getting it to Lisbon and thence to England, makes it cost about $15a 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 phosphoriteshipped from Spain, the mode of its occurrence differs from that in theLogrosan district. While in the latter it occurs in veins, sometimesof considerable length/ at Caceres it occurs in
Bulletin of the United States Geological Survey--The Nature and Origin of Deposits of Phosphate and Lime . rips a week, carrying 40 to 50 cwt. each trip. This, with the expenseof getting it to Lisbon and thence to England, makes it cost about $15a 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 phosphoriteshipped from Spain, the mode of its occurrence differs from that in theLogrosan district. While in the latter it occurs in veins, sometimesof considerable length/ at Caceres it occurs in pockets in great veins ofquartz 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 The first four, being the onlymines of much importance, will alone be described. As will be seenfrom the ground plan (Fig. 25), the limestone and quartz veins, inwhich the phosphate is found, occur in both the granite and the 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 Caceresmines. There are two veins penetrating the side of a hill in a north 1 C. U. Shepard, jr., MS.(530) PKXEOSE.] PHOSPHORITES OF SPAIN. 57 and east direction, respectively, at an angle of about 45°. The vein tothe north has a thickness of ten to twenty feet, and contains a variablequantity of limestone and siliceous rock. The immediately surroundingrock is limestone of a hard, brown character, which has been excavatedfor a depth of some one hundred feet (1875). The leads appear tonarrow as they are followed into the hill. The exterior of the mass ofphosphate is hard, white, and compact, while
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