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Wada K„ Ólafur Arnalds, Y. Kakuto, L.P.
Wilding & C.T. Hallmark 1992. Clay
minerals of four soils formed in eolian
and tephra materials in lceland. Geo-
derma 52. 351-365.
SUMMARY
Notes on clay minerals
in Icelandic soils
By Olafur Arnalcls
Agricultural Research Institute (RALA)
Keldnaholt
IS-112 REYKJAVÍK
Iceland
The paper describes in general terms the
formation of clay minerals in soils. It pro-
vides discussion on minerals that are com-
mon in volcanic soils (Andosols), which
are allophane, ferrihydrate and imogolite.
It has been assumed that Icelandic soils
are poor in soi! clays since traditional
methods to measure particle size reveal
limited clay content. X-ray diffraction has
also shown lack of layer silicates. This is
common for volcanic soils, even if clays
are an important constituent of the soils.
Alternative methods have to be used for
analysis of clays in volcanic soils. These
include chemical analysis (e.g. oxalate
extraction), infrared analyses, transmis-
sion electron microscopy and high energy
dispersion for particle size analyses.
Results of such analyses based on Wada
et al. (1992) and Ólafur Arnalds (1990),
are presented in Table 2. Allophanes,
imogolite and ferrihydrate are contmon
minerals in lcelandic soils, but layer sili-
cates are uncommon.
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