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A Comparison of the Methods of Heavy Mineral Separation

Published online by Cambridge University Press:  01 May 2009

C. J. C. Ewing
Affiliation:
King's College, London.

Extract

Methods and apparatus used in the isolation of heavy minerals vary considerably with different workers and this lack of uniformity obviously reduces the value of the conclusions in a branch of petrology in which quantitative data are essential. Panning in water and separation in bromoform are probably the two methods most widely adopted; but even with these there is considerable variation in the apparatus, each investigator using his own special panning device or type of separator. Also, whereas some writers employ direct bromoform separations, others treat the sediment by preliminary panning, and still others are content with panning alone. A paper published recently by Dr. F. Smithson showed the effects of panning on a crushed sandstone from the Yorkshire Trias and the results were compared with those of direct bromoform separations. The divergence of results was so great that it seemed worth while to carry out a similar type of investigation on some normal unconsolidated sands in which the heavy residue makes up about 0·2 to 0·3 per cent of the total bulk. The samples used in this case were mostly from the northern outcrop of the Folkestone Sand in the Weald, but some samples of Eocene Sands from the Continent were also examined.

Type
Original Articles
Copyright
Copyright © Cambridge University Press 1931

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References

page 136 note 1 Geol. Mag., LXVII, 1930, 134–6.Google Scholar

page 138 note 1 It will be noticed that the figures have been taken to the nearest 0·5 per cent. It is obviously impossible to work to an accuracy entailed by the first decimal point, but in the case of the smaller numbers, approximation to the nearest whole number is more serious than with the larger numbers, so a compromise has been adopted, and all figures are taken to the nearest 0·5 per cent.