SANDS:
(a) Drawing of sand grains from soil. Note
that the particles are irregular in size and shape. Quartz usually predominates,
but other minerals may occur. Silt size particles have the same general
shape and composition, but they differ from sands in size. The figures
on the right are scanning electron micrographs of (b) quartz sand, and
(c) a feldspar grain. The magnification in these pictures is about 40 x.
Original photos by J. R. Glasmann, Union Oil Research.
Diagram published in Brady, The Nature and Properties of Soils, 9th Edition,
Macmillan Publishing Co.
CLAYS:
Kaolinite magnified about 1,600 times:
Dickite magnified
about 9,000 times:
Illite magnified
about 15,000 times:
Montmorillonite magnified
about 18,000 times:
All
photos taken by Dr. B.F. Bohor, Illinois State Geological Survey. Published
in Brady, N.C., The Nature and Properties of Soils, 8th edition, Macmillan
Publishing Co.
Photomicrograph showing a natural arrangement of soil particles:
Original
photo taken by Steve Thien, Published
in Troeh, F.R. & L.M. Thompson, Soils and Soil Fertility, 5th edition, Oxford University Press
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