# III. Estimate of Quantity

### III. Estimate of Quantity.

The ironstone being in many places of so open a structure that it would be useless to take the specific gravity of a number of samples with a view to finding that of the whole, I have assumed this to be 2.8; thus making a cubic foot weigh 175 lb.

I was unable to do more than take a number of aneroid readings, and so estimate the height of the main hill: this appears to be about 200 feet. Acting page 57 on these assumptions, I have made the following calculations:—
 A. Average height 200 feet Average width 950 feet Average section 119,700 square ft., but deducting one-third for gullies, this becomes 79,800 sq. ft. Length 8,316 feet No. of tons of hematite 51,835,600 B. Average height 34 feet Average section 5,100 sq. feet Length 2,100 feet No. of tons of hematite 836,719 C. Average height 14 feet Diameter 310 feet No. of tons of hematite 82,553 D. Average height 10 feet Diameter 75 feet No. of tons of hematite 3,450 E. Average height 10 feet Diameter 75 feet No. of tons of hematite 3,450 F. Average height 20 feet Diameter 240 feet No. of tons of hematite 70,686 G. Average height 20 feet Diameter 90 feet No. of tons of hematite 9,927 H. Average height 20 feet Diameter 120 feet No. of tons of hematite 13,254 I. Average height 50 feet Diameter 132 feet No. of tons of hematite 37,419 Total No. of tons of hematite 52,893,058
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In this estimate no ore lying outside the boundary-line is included, nor are the deposits at K and L.

Between the small hills F and G and the main hill is a small knob of about the same size as F, which is to all outward appearance solid hematite; in this, however, is an excavation, about eight feet in depth, exhibiting the following section:—
 ft. in. Ironstone with many quartz pebbles 1 6 Clay 6 6

This shows that the mass of the hill is clay, with merely a shell of hematite. From this fact I am doubtful as to whether this may not occur in a good many cases; but it could be proved only by boring.

Without this aid no accurate estimate of the quantity of hematite can be made.

I have, &c., (Signed)

George J. Binns, M.E.

Wyman and Sons, Printers, Great Queen Street, London, W.C.