1S91.J 
256 
[Whittle. 
pact “kidney ore ’’and the porous variety occurring at Quaco made 
by Dr. A. M. Comey of Harvard College. 
Kidney Ore. Per cent. 
Porous Ore. Per cent. 
Manganese Dioxide 
71.54 
Manganese Dioxide 
65.00 
Metallic Manganese 
58.20 
Metallic Manganese 
57.15 
Insoluble Silicates 
8.37 
Insoluble Silicates 
6.66 
Ferric Oxide 
2.19 
Ferric Oxide 
1.75 
Phosphorus 
0.02 
Phosphorus 
0.04 
Calcium 
trace 
Calcium 
trace 
Sulphur 
0 
Sulphur 
0 
Three unvarying phenomena are associated with the occurrence 
of manganese in the three localities above mentioned : firstly, the 
presence of phosphorus and iron in all varieties : secondly, the 
distribution of the ores in or with a limestone or red clay hori- 
zon ; and thirdly, the presence of a practically impervious stratum 
at the base of the ore-carrying bodies. The first two factors point 
towards the source of the manganese ; the last one indicates the 
conditions under which manganese deposits were formed and why 
they occupy their present position as true bedded deposits. In 
Sir C. Wyville Thomson’s contribution to our knowledge of the 
character of the deep sea phenomena the association of mangan- 
ese nodules with red clay deposits and the uniform presence of 
phosphorus and iron in these is mentioned . 1 Analyses made by 
Mr. Buchanan showed the manganese to be chemically combined 
as the peroxide and that by a process of substitution earthy 
peroxide appears to be changing to brilliant accilar crystals of 
pyrolusite, occurring scattered irregularly through the spongy 
earthy nodules . 2 This, too, without hydration. Chemically the 
manganese occurs in the same combination in the porous nodules 
in the deep sea as in the most porous ores found at Quaco, and 
it is noticed that the phosphorus is much more abundant than in 
the compact “kidney ore,” being nearly double in quantity. The 
processes, begun before the induration of the deep-sea deposits and 
before their elevation from the sea bottom that tend to convert 
semi-crystalline into well-formed crystalline ore, are still going on 
in the red, calcareous shale and limestone, and the most porous 
nodules which simulate so closely both chemically and physically 
Voyage of the Challenger, vol. ii. pp. 7-8. 
2 Ibid, p. 8. 
