BLACK SANDS OF PARACALE. 935 
TABLE XVII.—Percentages of total gold in nonmagnetic and magnetic 
portions. 
Gold in ‘ 
Gold in 
Screen. nonmag: mapnetie! 
Mesh. Per cent. | Per cent. 
OMe eae esa eoes Sheesh cue oben ess ese ae sect soaeckoteese oe 23.00 0.70 
20 bee ae esse a SocS eS. 32a sess sect asnecehesgecceanse shee se 35. 30 0.97 
1 () ee a a ee ae ee ee Sane 13.80 0.31 
G0 Ee aaa sete See oe eo wee we dos se neti esscsscscdesdeese 7.80 0.14 
BS ee Gas See Se a eae a pete pee 7.80 0.18 
OO Fee eee Sasa se bes Sac ee seas shee ue Sena ee tesseseeek 2.97 0.14 
1 50 ee eee ee eee Pose nt eA Ooo oe eee 3.37 0.13 
YE es Sn 3.37 0.13 
Dota ese a oak oe 2 eee sdb s vaacoscsetaetessesstese 96.51 2.94 
This table shows that 23 per cent of the gold in the original 
is found with the 10-mesh nonmagnetic, 35.3 per cent is found 
with the 20-mesh nonmagnetic, etc. The decrease in percentage 
with the finer meshes is clearly shown. 
The association of only 2.94 per cent of the gold with the 
magnetic would indicate the efficiency of magnetic separation to 
eliminate a large bulk of low-grade tailings and leave a small 
bulk of high-grade concentrates for shipment. Where the cost 
of shipping is a factor, as in the Paracale district, the importance 
of these results can hardly be overestimated, as they indicate the 
possibility of concentrating the values into a small high-grade 
product and thus making a great saving in the cost of shipping 
and smelting. 
In order to determine the effect of magnetic separation upon 
the dredge tailings, a large sample was taken, panned by hand, 
and concentrates obtained. These concentrates (lot 3) assayed 
16.40 pesos per ton, and a portion was separated into non- 
magnetic and magnetic products. The nonmagnetic product, 
weighing 880 grams, assayed 24 pesos per ton; and the magnetic 
product, weighing 630 grams, assayed 5.82 pesos per ton. This 
test again proved the marked association of the gold with the 
nonmagnetic material. 
A Wilfley-type table treating the dredge tailings would prob- 
ably give concentrates equal to the value of lot 3, or 16.40 
pesos. Such a product could not be magnetically treated with 
the object of shipping the nonmagnetic product, for such a 
product, as indicated, would have a value of only 24 pesos. This 
is insufficient to pay shipping and smelting charges. Should a 
large bulk of 16-peso product be obtained by concentration tables 
