BLACK SANDS OF PARACALE. 929 
TABLE XII.—Second panning test. Lot No. 1. 
(Ore crushed through 40-mesh.) 
Assay Value 
Product. Weight. Neue ver See a Sore 
product. uitonien 
original. 
Grams. | Per cent.| Pesos. Pesos. | Per cent. 
Original heads________-_--__-_- 200) Peers 210.30 P2IORSO Rea 
(Goldirecovered essa sense aes | ener e ren =| eee eee ae 91. 80 43.50 
Tailings: 
Nonmagnetic_---_------__- 91.4 45.7 102. 80 51.00 24.3 
IMaeneticmese= at ee ee 107.5 53.7 13.20 7.10 2.9 
Loss in slimes -___------------- iba] 0.55 61. 40 61. 40 29.3 
As seen from this table, from 1 ton of concentrates, 91.80 
pesos or 43.5 per cent of the gold was saved as free gold by 
means of panning. The tailings had a value of 51.40 pesos per 
ton. If these tails were treated magnetically, we could obtain 
a nonmagnetic product worth 102.80 pesos per ton and a 
magnetic product worth 13.20 pesos per ton. If we consider 
the gold and the nonmagnetic product, we find a total saving 
of only 67.8 per cent of the gold by a method involving (1) 
erushing through 40-mesh, (2) concentration on a Wilfley-type 
table, followed by (3) magnetic treatment of the tailings. Such 
a saving is too small for practical consideration. 
A salient feature of these preliminary tests was the fact that 
a large percentage of the gold is so fine as to be lost in the slimes 
even under the most careful conditions of panning. 
Similarly, dredging must lose a large amount of this type of 
gold. In addition, dredging loses practically all of the gold 
bound up in the black sand and quartz. The black sands saved 
in the cleanups are negligible in comparison with the amount 
present in the ground, and the quartz boulders picked out of 
the chutes represent only a small fraction of the quartz present. 
It would seem apparent that dredging is losing more than 50 per 
cent of the total gold, free and combined, in the ground. These 
figures have been confirmed by sampling the dredge tailings, 
concentrating and assaying them, estimating the total amount 
of this class of sand wasted, and comparing the result with the 
output of the dredge. This does not mean that the dredge lost 
50 per cent of the value of the ground as estimated by drive-pips 
tests. The drive-pipe tests themselves merely show the free gold 
and hence probably show less than 50 per cent of the gold actually 
in the ground. 
113321——2 
