I have generally found that reports of grades are usually expressed per
square fathom, when cubic fathoms are indicated they are usually expressed
explicitly as cubic.
Geoff Treseder
-----Original Message-----
From: Martin Critchley
Sent: Monday, June 18, 2012 2:05 PM
To: [log in to unmask]
Subject: Ore grades - tons per fathom
Often the grade of ore in a vein in the C19th is quoted in tons or cwts per
fathom. I assume that this means the weight of ore per cubic fathom (not a
linear fathom). For example if the grade is quoted at 1 ton per fathom,
then am I correct in the following calculation:
1 cubic fathom is about 6 cubic metres. 1 ton of galena is about 0.14 cubic
metres in volume taking a specific gravity of 7.5. Thus 1 ton per [cubic]
fathom lead ore grade = 0.14/6 which is approximately 2.5% lead ore
Martin
Dr. Martin Critchley, ERA-Maptec Ltd., 40 Lower O'Connell Street, Dublin 1,
Ireland2*.9
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