BLACK SANDS OF PARACALE. a7 
An important characteristic of this sand is the large amount 
of iron pyrites caught on the 10-mesh screen and the compara- 
tively small amount caught on the 20-mesh screen. ‘Tests made 
in connection with this investigation have shown that in all 
probability the values in the black sands other than free gold are 
largely due to the richness of these pyrites. 
The nonmetals are unimportant. Of these zircon is probably 
the most abundant. It is found in characteristic crystals of 1 
millimeter or less in length. The small amount shown in the 
screen test is no indication of the amount of this heavier non- 
metal actually present in the original sands. The character of 
the rock formation of the district is such that large amounts 
of garnet, zircon, pyroxene, and biotite should result from its 
weathering, and should concentrate with the black sand. In- 
significant amounts of metallic iron, galena, and metallic lead are 
found in the table concentrates. The iron and metallic lead are 
undoubtedly, for the most part, foreign materials derived from 
the dredge or dredge operation. Copper coins, rings, and various 
metallic articles manufactured by man have also been found. 
Several distinct classes of gold are found. One class is very 
light yellow, well crystallized, and is usually found attached to 
quartz grains (Plate 1). Some pieces are so light in color as to 
appear nearly white, probably due to a large silver content. The 
second class is also crystalline and associated with quartz, but 
is of a much darker color, apparently being stained with iron 
oxide. The third class is generally yellow, but shows decidedly 
worn and rounded surfaces as if it had traveled a greater dis- 
tance than the majority of the gold. The fine gold is crystalline 
and angular, showing that it had moved but a short distance from 
its source. A. large number of perfect octohedrons was notice- 
able. These were very small and would for the most part pass 
an 80-mesh screen. These crystals were often joined, forming 
trees of wire gold. 
DREDGE OPERATION. 
At present the placer deposit is worked by a 3.5-foot loose- 
connected, or link-bucket, type of dredge which has been able to 
handle about 10,000 cubic meters of material per month, although 
designed to handle from 20,000 to 25,000 cubic meters. The 
buckets at present dump into a revolving screen or trummel, 
which serves merely to break up the clay and to screen out the 
boulders and pebbles greater than 1 inch in diameter. The 
screen product passes over a series of tables fitted with cross 
riffes underlain with coco matting. These riffles quickly become 
