The Origin and Composition of Pyrolusite Concretions 
in Hawaiian Soils 1 
G. Donald Sherman, Annie K. S. Tom, and Charles K. Fujimoto 2 
The soils of the drier regions of the Hawaiian 
Islands have a very high manganese content. 
Kelley (1909) has reported that certain dark- 
colored soils which are closely associated with the 
red soils have an Mn 3 0 4 content ranging from 
2.4 to 9.7 per cent. He has indicated the rela- 
tionship between the poor growth of pineapples 
and the high manganese content of these soils 
(1909, 1910). In a later publication Kelley 
(1912) described the occurrence and distribu- 
tion of the manganiferous soils on the island of 
Oahu. He pointed out that within the bound- 
aries of the manganiferous soils there were areas 
of variable sizes where pyrolusite concretions 
appeared to have accumulated. These areas have 
been observed by many workers since the pub- 
lication of Kelley’s work. In some of the irriga- 
tion ditches it is possible to gather large num- 
bers of these concretions which have been con- 
centrated by the irrigation water. 
The origin of these concretions has been the 
subject of much speculation. Kelley (1912) has 
suggested two possible hypotheses. The first 
states that the formation of the concretions took 
place while the island of Oahu was submerged. 
This theory is supported by the similarity be- 
tween the chemical composition of the concre- 
tions found in the soils of the island of Oahu and 
the composition of concretions from the floor 
of the Pacific Ocean as reported by Murray and 
Renard ( 1891 ) . Pyrolusite concretions are often 
found in the sediments of fresh-water lakes. The 
1 Published by permission of the Director of the 
University of Hawaii Agricultural Experiment Station 
as Technical Paper 173. Manuscript received July 7, 
1948. 
2 University of Hawaii Agricultural Experiment Sta- 
tion, Honolulu, Hawaii. 
second theory of the origin of these concretions 
is that the manganese has become soluble by 
the weathering of the basalt lavas and has 
leached to the lower elevations in drainage 
Waters where it becomes oxidized and is pre- 
cipitated around various nuclei. 
During the summer of 1947 the senior author 
discovered a large number of pyrolusite concre- 
tions formed around the roots of a shrub on the 
island of Lanai. A closer examination revealed 
that a thin layer of MnO a had been deposited 
around all of the roots and that concretions had 
developed at certain points along the root of the 
plant. The concretions, when separated from the 
root of the plant, were tubular in shape. Further 
examination of the concretions in the soil re- 
vealed that the majority of them had been 
formed by their precipitation around roots of 
plants. As a result of this discovery a study has 
been made to determine the nature, origin, and 
composition of pyrolusite concretions occurring 
in Hawaiian soils. 
A number of concretions have been collected 
from several typical manganiferous soils. In each 
case evidence was gathered as to the possible 
origin of the concretion. From these examina- 
tions it is very likely that all of the concretions 
have been formed by the oxidation of soluble 
manganese and its precipitation around nuclei. 
The deposition of Mn0 2 occurs in root chan- 
nels, in cracks in the soil, around roots of plants, 
on surfaces of soil granules, and in the non- 
capillary pores of the soil. The shape of the 
concretion is determined by the manner of 
deposition. The spherical forms have developed 
where the Mn0 2 has been oxidized and depos- 
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