Laterite of Meyer Lake, Molokai — Sherman et al. 
n 
TABLE 1 
The Chemical Composition of a Titaniferous-Ferruginous Laterite 
Located on Slope to Meyer Lake, Molokai 
DESCRIPTION 
DEPTH 
INCHES 
Si0 2 
PER CENT 
AI2O3 
PER CENT 
Fe 2 0 3 
PER CENT 
Ti0 2 
PER CENT 
MnO 
PER CENT 
Surface — grayish purple indurate 
layer rich in ferruginous con- 
cretions 
0-12 
8.78 
12.16 
45.98 
19.22 
0.19 
Friable reddish brown silty clay . . . 
12-20 
12.03 
16.70 
41.64 
19.56 
0.17 
Rotten gray lava rock — weathered 
20-34 
24.80 
47.10 
6.60 
9.20 
0.22 
Bluish gray silty clay 
34+ 
17.69 
46.16 
12.84 
2.03 
0.07 
The analysis of this profile shows that the 
chemical composition is similar to that of the 
soils of other profiles of the Naiwa family as 
reported by Sherman et al. (1949) and Sher- 
man (1949, 1952). The iron oxide and titan- 
ium oxide contents were found to be high in 
the soil solum, being 46 and 42 per cent for 
iron oxide and 19 and 20 per cent for titanium 
oxide. The low silica content and the absence 
of alumino-silicate minerals, montmorin and 
kaolin, indicate the degree of the intensity 
of chemical weathering. Desilication has pro- 
gressed to the point where these minerals 
have decomposed. The chemical composition 
of the rotten lava is similar to that found in 
other locations. Differential thermal analysis 
identified kaolin as the dominant mineral in 
the weathered material adjacent to the rotten 
rock. 
The data presented in Table 2 show the 
chemical composition of the samples taken 
across the indurate area, Figure 1. The tita- 
nium oxide content of the samples ranged from 
10.2 to 20.6 per cent with the highest levels 
occurring within the dehydrated indurate 
area. The titanium oxide content of the con- 
cretions was approximately one-half of that 
found in the soil of the same sampling site. 
The concretions retained on a 40-mesh screen 
amounted to 30 to 43 per cent of the weight 
of the soil. The iron oxide content of the soil 
ranged from 33.1 to 57.4 per cent in the in- 
durate area as compared to 21.4 to 37.6 per 
cent in the hydrated reddish brown soils. The 
iron oxide content of the concretions was very 
high, ranging from 65.7 to 74.6 per cent. 
Aluminum oxide content of the soil and the 
concretions from the indurate area was very 
low. The silica content of the concretions was 
extremely low with 4.1 per cent being the 
greatest percentage found. 
The ferrous and ferric iron contents of the 
soil were determined in order to estimate the 
percentage of ilmenite present in the soil. The 
iron occurring in ilmenite (FeO • Ti0 2 ) is in 
the ferrous form. One can assume that the 
ferrous iron in the soil may exist in the mineral 
ilmenite provided weathering has progressed 
under conditions of excellent oxidation and 
drainage. However, it is known that ferrous 
iron can exist in other minerals common to 
advanced stages of weathering such as mag- 
netite (2 FeO • Fe 2 03 ). The results of the 
ferrous and ferric iron determination are giv- 
en in Table 3. 
The data in Table 3 show that the ferrous 
iron content of the concretions is much lower 
than that found in the soil. The ferrous iron 
content of the concretions was 3.3 and 4.1 
per cent; in the soil it ranged from 12.0 to 
14.8 per cent. When the ilmenite content is 
calculated from the ferrous iron content, there 
is an excess of free titanium oxide in the 
concretion. Some free titanium oxide does 
