Reézamination of American Minerals. 253 
In another group of crystals the pyrites in equally small crys- 
tals is found in three lines on the summit of every crystal run- 
ning from the apex towards the edges, exactly bisecting each face 
as seen in figure 6. 
In this instance, as well as in the former, the pyrites is inserted 
entirely beneath the surface of the crystal, which is perfectly 
smooth. 
The calcite is found in large crystals in dolomite, and is 
associated with most of the ores of the mine. It sometimes 
gives rise to pseudomorphs of molybdate of lead and carbonate 
of lead; these pseudomorphs are mere shells however, retaining 
the form of the calcite. 
64. Sulphur. 
Sulphur occurs in the form of small pale greenish yellow crys- 
tals; they are transparent and disseminated through cellular ga- 
lena which appears to have undergone partial decomposition ; the 
galena in which it occurs is frequently associated with copper 
and iron pyrites and in some rare instances with carbonate and 
phosphate of lead. 
The other minerals occurring in the Wheatley mine are finely 
crystallized quartz, oryd of manganese, iron pyrites, sulphate of 
aryta, indigo copper, black oxyd of copper, and dolomite. 
the other mineral veins in this region, none have yielded 
the beautiful mineral species furnished by the Wheatley vein. 
"he Perkiomen vein, five miles from the Wheatley vein, has fur- 
nished fine capillary copper, indigo copper, fine acicular crystals 
of sulphate of baryta, crystallized copper, and some crystals of 
sulphate, carbonate and yellow molybdate of lead, but these last 
were small and bear no comparison to those described. 
It was hoped that something might be learned concerning the 
formation of the minerals of this vein, but the difficulties and un- 
