I44 NEW YORK STATE MUSEUM 
apex to the center of the face or half an inch along a crystallo- 
graphic axis. Most of the crystals of chalcopyrite are between 
one-sixteenth and one-eighth of an inch in diameter and are usu- 
ally found in the cellular structures associated with calcite and 
quartz. It has also been found in veins, where it appears to have 
a later age than the quartz because of its position as an inter- 
stitial ingredient between the box components of the breccia. 
In other words as a vein, chalcopyrite appears to have followed 
or conformed to the quartz plates. In the main part of the vein 
the walls are of crystalline quartz which would be evidence of an 
earlier age for the quartz. As only one specimen of the vein has 
been found little can be said about its relationship. 
Disseminated grains and crystals of chalcopyrite are occasionally 
seen in the silicified Grenville marble of the footwall series 
(c) where it is associated mainly with quartz and calcite. In this 
occurrence the quartz apparently would be its carrier. 
More recent changes brought about by oxidation and carboniz- 
ation have altered the chalcopyrite to limonite and malachite; in 
fact pseudomorphs of the limonite after chalcopyrite are quite 
common. 
Sphalerite. This mineral is neither as well crystallized nor as 
abundant as the others described above. It is usually honey 
yellow in color, of resinous luster and poorly crystallized but 
having the same associations as chalcopyrite. In one specimen 
could be seen what was left of a small crystal of sphalerite, very 
much corroded and about it a zone of amorphous light colored 
smithsonite incrusting calcite crystals. The effect of carbonic 
acid bearing waters upon the suphide was doubtless responsible 
for the corrosion and the formation of the carbonate as well. 
Pyrolusite. Dendritic pyrolusite frequently occurs in the 
banded structures and on the quartz plates where it is found as 
a result of oxidation of the carbonate which is usually found 
adhering to the quartz as described above. 
Kaolin. In some of the cellular structures, particularly the 
boxes, is found a claylike substance, of greenish gray color for 
the most part, but occasionally dark or black, associated with a 
light colored micaceous mineral of pearly luster and angular 
grains of quartz. The claylike substance is essentially a kaolin, 
a residual product of the original contents of the breccia in all 
probability. 
