IS 9 I.J 
[Whittle. 
255 
mere films. The veins in the limestone are minute threads of ore 
crossing it irregularly for a short distance and then disappearing, 
and are associated with numerous round to elliptical areas of 
the same. 
Vermont ores of manganese occurring in Rutland and Winsor 
counties are similarly associated, although the country rock is 
Lower Cambrian and their geological position is at the base of 
the Stockbridge limestone as irregular lenses and small areas of 
porous earthy ore, carrying a large percentage of iron, in yellow 
or white clay. The limestone lying conformably on a flinty quartz- 
ite affords an excellent water way, and its alteration to clay has 
liberated the ore so that it can carry now be removed simply with 
pick and shovel. Here as at Quaco the rock at the base of the 
ore-carrying stratum is one of the least porous varieties. A 
section across the ore-bearing horizon in which the Crimora 
ores are found in Virginia presents the same association as found 
in Vermont. There again the manganese, occurring mainly as 
“kidney ore’’ is found in lenses and scattered masses in yellow 
clay, the product of a decomposed limestone such as makes the 
surface of the country in that region, which lies on a micaceous 
quartzite or quartz schist, — the layer of ore-bearing clay being 
next the quartzite. In the geology of the Virginias these rocks 
are classed as Silurio-Cambrian . 1 One stalactite weighing sev- 
eral pounds was given me by a miner at Crimora who assured me 
he had found it pendent from the roof of a small limestone cav- 
ern. In Vermont lenses and geodes of limonite occur with stal- 
actites of psilomelane traversing the interior like bars. These 
bars in section show concentric bending. 
As regards the source of manganese nodules one cannot fail to 
notice the similarity of the more porous, earthy variety of ore 
occurring at Quaco to the manganese nodules found by dredging 
in the deep sea during the voyages of the Challenger and Blake. 
The two nodules not only resemble each other physically but 
chemically the resemblance is still more marked. Phosphorus 
exists in much larger amounts in the deep sea nodules and their 
specific gravity is less owing to their porosity. Analyses of the 
ores uniformily show the presence of phosphorus and iron in 
varying amount. The following are partial analyses of the com- 
Rogers, Report reprinted in 1884. 
