TRANSACTIONS OF WAGNER 
MINERALOGY OF THE NEWARK GROUP IN PENNSYLVANIA 
20 
found to be soluble in dilute sulfuric acid, when boiled in a current of carbon 
dioxid, and has therefore been calculated as siderite, although the significance 
of the presence of this mineral is not clear. The water given off below 110° 
has not been used in the calculations, as it probably represents what is mechanic- 
ally held in the fine powder; the amount found above this temperature agrees 
almost exactly with the theoretical percentage present in the kaolinite calculated 
from the alumina. The percentage of these minerals obtained is as follows: 
A / ME Dod ноа 69.38 
Teo Eo! ,,, nnd. 15.60 
Меде Fes ОИ РИ CIA DL д: 4.67 
eee, ne A en, 1.78 
hn, ñᷣ ОЕА pe тон 8.48 
100.00 
The mottled red and gray phase of shale occurring some sixty feet below 
the base of the intrusive sheet appeared to be well adapted to determine the 
nature of the alteration produced by the heated waters given off during the 
solidification of the trap. A specimen three inches long was obtained, bright 
red at one end and pale gray at the other, and samples from the extremities were 
analyzed in the same manner as the unaltered shale described above. ‘The red 
portion contained: 
SOLUBLE IN HCl. INSOLUBLE tn HCl. TOTALS. 
SiO,..... 2 0.33 77:37 77.70 
M,, eua e Ud 4.09 5,08 9.72 
Dead Wa iu alle 3.94 2.41 6.35 
OG Ur er ТЫ; ЖА 0.69 0.69 
G Ии D^ 2.10 2/27. 
N a ея „ж 0.09 0.09 
FFF Be eee 0.52 
МП, т... 4. ... wine here "en 1.56 
09.00 
In the attempt to assign the results to various minerals an unexpected 
difficulty was encountered. Study of a thin section of this shale had shown the 
presence of a dull brownish mineral, agreeing with epidote in optical character, 
surrounding the quartz grains. Proceeding on the assumption that the calcium 
oxid was all present in this form, and calculating the corresponding amount of 
alumina, an excess of the latter, a considerable part of which is soluble in 
hydrochloric acid, was found to remain. While this may exist in part as unal- 
