Calcareous Concretions — Sherman and Ikawa 
257 
TABLE 1 
The Chemical Composition of the Carbonates in Rhizo-concretions and 
Calcareous Layers Occurring in the Soils of the Pakini Series, South Point, 
Kau, Island of Hawaii 
Sample 
Total 
CARBONATES 
Minerals 
OTHER THAN 
CARBONATES 
CaC0 3 
IN 
SAMPLE 
MgCOs 
IN 
SAMPLE 
Carbonates 
as 
DOLOMITE 
CaCOa 
Y — 
MgCOa 
Per cent 
Per cent 
Per cent 
Per cent 
Per cent 
Rhizo-concretion 
#1 inner portion 
81.6 
14.2 
58.5 
23.1 
62.1 
1.61 
Rhizo-concretion 
#1 outer portion 
66.1 
25.3 
49.1 
17.0 
56.5 
1.77 
Rhizo-concretion 
jf2 inner portion 
81.7 
14.4 
58.4 
23-3 
62.5 
1.60 
Rhizo-concretion 
jf2 outer portion 
65.4 
25.2 
48.9 
16.5 
55.2 
1.81 
Calcareous sheet /I 
67.3 
28.6 
49.3 
18.0 
58.4 
1.71 
Calcareous sheet #2 
67.3 
28.5 
49.4 
17.9 
58.2 
i.72 
bicarbonate which would be essential to the 
process of dolomitization. Since calcium ions 
occur in a greater concentration, the precipi- 
tated carbonates would show an excess of cal- 
cium carbonate. Thus, the rhizo-concretions 
and sheets should be considered to be dol- 
omitic lime depositions. 
SUMMARY 
The results of this study have resulted in 
the following conclusions. The highest total 
carbonate and carbonates in the form of dolo- 
mite occur in the inner portion of the cal- 
careous rhizo-concretions. The similarity be- 
tween the composition of the outer portion of 
the rhizo-concretions and the calcareous 
sheets indicates that these concretionary depo- 
sitions occurred under the same conditions 
and are undoubtedly deposited by the same 
process. The proportion of magnesium car- 
bonate in all of these concretions indicates 
that active dolomitization is occurring and 
that dolomite is being deposited in the concre- 
tion. These concretions should be considered 
as dolomitic lime concretions. 
REFERENCES 
Bryan, W. H. 1952. Soil Nodules and Their 
Significance . Sir Douglas Mawson Anniver- 
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Gillam, W. S. 1937. The formation of lime 
concretions in the Moody and Crafton 
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Mathias, H. E. 1931. Calcareous sandstone 
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