146 GEOLOGICAL RECONNOISSANCE 
to be carefully examined (the analyses of a few of them you will find 
detailed on p. 176, etc.), in order to establish a rational connexion between 
the general geological features of the country and the mineral deposits, 
and to discover, if possible, the hidden cause which occasioned the for- 
mation of such extensive deposits, and exercised so powerful a pseudo- 
morphic action as is evidenced in that part of the state. 
I beg leave to call your attention, in the next place, to the analyses of 
the ores of manganese. You will perceive, by a glance at the table on 
p. 166, that the analytical results here are also very favorable; the ores 
are valuable to the bleacher, the paper and the glass manufacturer, and 
I confidently believe, that by pursuing a rational system of mining, and 
examining carefully the neighborhood of the veins on Lafferty creek, an 
ore still more valuable, the “pyrolusite” of the mineralogists will be dis- 
covered, an opinion based on the observation: that the last mentioned 
mineral almost invariably occurs associated with psilomelane and brau- 
nite, the minerals already found. I have endeavored, on p. 167, etc., to 
establish rational formulas for the composition of these ores, in the expec- 
tation of throwing some light on the mutual chemical relation which the 
various, so closely connected minerals, bear towards each other; I hope 
that the continuance of the survey may enable me, by an additional series of 
analyses, to draw some general conclusions as to their formation, mutual 
relation, and probable origin. 
As to the remaining portion of my Report, no further remarks appear 
necessary: the analyses speak for themselves. . 
The reasons which prompted me to append a chapter on the “ methods 
of analysis,” I have given below. 
All which is respectfully submitted, 
WILLIAM ELDERHORST, 
Chemical Assistant. 
