White Limestones of Sussex Count //, i\T. J. — Xason. 157 
Usually the "vein matter" of the ore body is carbonate of 
lime, which, owing to the presence of manganese, turns black 
after a short exposure to the weather. It is usually free 
from magnesian carbonate. This is also generally true of a 
belt of limestone, from one to ten feet thick, on the hanging 
wall side of the mine. 
After the bore hole in the foot wall was finished, the drill 
was turned into the hanging wall. See fig. 2, }*-b. The drill 
passed through a small lens of ore and then for twenty feet 
into pure limstone. As before, the core was tested with acid. 
About two feet of the core effervesced freely, the balance did 
not. Samples of the part which did not effervesce were taken 
and analyzed, with the following result: 
IV. 
Insoluble 10.28 
Fe, O s -|-Al 2 3 2.25 
CaC0 3 50.82 
Mg CO3 36.52 
Total 99.87 
This is again a dolomite. It is especially interesting since 
it is found in the hanging wall less than ten feet from the ore 
body. The limestone is a dark bluish gray, rather than white. 
There is a good deal of sphalerite and pyrite in crystalline 
grains. The end of the core, near the point, in fig. 2, is al- 
most a calcareous sandstone, the silica being present in clear 
grains. The fact that the high percentage of insoluble mat- 
ter, 10.28, is due to silica, was proved by treatment with 
hydrofluoric acid. All was volatilized except .75. 
Analyses I, II, III and III 1 show very conclusively that tin- 
outcropping magnesian limestone which forms the foot wall 
of the ore body, and occurs between that and the gneiss, is 
persistent to the depth of at least four hundred feet from the 
surface. Another analysis shows that this bed reaches still 
farther. A piece of the core from the drillhole No. 5 (see 
fig. 1), 1,100 and 1,111 feet from the surface, and below the 
ore body, gives the following: 
V. VI. 
Insoluble 0.20 0.03 
Fe., O.; +A1, O.j 3.95 0.31 
Ca"c6. { .' 55.91 93.99 
Mg CO., 39.68 5.48 
Totals 99.74 99.81 
