216 FANNING AND EDDINGFIELD. 
The second is described as follows:° 
From 0 to 1.5 meters, soil, nipa, etc. 
From 1.5 to 7.6 meters, sand and gravel with some values. 
From 7.6 to 11.5 meters, heavy black loam, with considerable decayed 
vegetable matter. 
From 11.5 to 12.2 meters, gravel, pay streak. 
The bed rock is white, soft, decomposed granite-gneiss. 
The first section must have been near the mouth of the Para- 
cale River below the contact of the gneiss and schist. 
DREDGE CONCENTRATES. 
The concentrates saved on the tables of the dredge are esti- 
mated to be as follows: 
TABLE I.—Composition of concentrates. 
Weight 
Mineral. (per cent.) 
Magnetite 51 
Ilmenite 16 
Pyrite 21 
Nonmetallic 12 
In examining the tables prepared by Day and Richards under 
magnetic separation of black sand in California, it is noted that 
ilmenite is found in comparatively few examples. The black 
sands of Paracale contain a large percentage of ilmenite. These 
grains almost invariably are well rounded and waterworn, but 
show practically no alteration or decomposition in a thin section. 
The ilmenite grains are among the largest caught on a 10-mesh* 
sieve, and are more abundant than the magnetite grains. This 
relation changes with the smaller sizes, and the magnetite con- 
tent increases until it becomes more than 50 per cent of the 
material. The magnetite is more angular than the ilmenite, and, 
while usually fresh, shows signs of oxidation and alteration. 
A screen test was made on a sample of about 2 kilograms of 
black sand, showing that on a 10-mesh sieve the material was 
approximately 25 per cent iron pyrites, 20 per cent magnetite 
and ilmenite, 2 per cent cemented black sand and quartz, and 5 
per cent nonmetallic. The material caught on the 20-mesh con- 
sisted approximately of 90 per cent magnetite and ilmenite, 6 
per cent iron pyrites, and 4 per cent nonmetallic. The percent- 
age of iron pyrites increases slightly in the smaller sizes, but 
definite estimates could not be made. 
*Smith, W. D., Min. Resources P. I. for 1909, Bur. Sci., Div. Min. 
(1910), 11. 
° The sizes of the various sieves used are given on page 223. 
