No. 60] 
71 
adjoining county vast beds which are extensively wrought. The ore in 
the town of Antwerp is interesting from its having associated with it 
crystals of quartz without prisms, and also a mineral new to this county, 
called cacoxenite. The latter, will be more particularly described in 
the appendix to this report. I have been informed that there is a valu- 
able bed of magnetic iron ore in the southern part of this county, but 
I was not so fortunate as to obtain specimens. Bog iron also occurs, 
but in consequence of the great abundance of the first named kind, it 
is not used in the manufacture of the metal. 
Small quantities of lead and copper ore have been found in various 
parts of Jefferson county, but their occm-rence has not yet led to many 
extensive mining operations. 
On the shore of Lake Ontario, a short distance N. E. of Sackett's 
Harbor, at a place called Pillar Point, is a locality of sulphate of ba- 
rytes, where the mineral may be taken out in large blocks. This sub- 
stance when ground is used as a paint either alone or mixed with white 
lead, of which last it has become a very common adulterant. 
Of the mineral called Rensselaerite by Dr. Emmons, but which has 
the composition of soapstone, there are several abundant localities in 
the vicinity of Oxbow. It is sometimes crystalline and sometimes 
compact, and deserves to be particularly noticed as it is often mistaken 
for plaster of Paris and has been used as a manure. Chemical analy- 
sis however shows that is chiefly composed of silica and magnesia, and 
it is not probable therefore that it possesses any fertilizing powers. 
To the mineralogist, this and the adjoining county (St. Lawrence,) 
are of great interest in consequence of the crystalline forms which 
many of its minerals assume. This is especially the case with the 
calcareous spar of which the varieties are almost innumerable. In the 
immediate vicinity of Oxbow, huge dodecahedral crystals have been 
obtained, which by cleavage furnish rhombohedrons, sometimes colour- 
less and sometimes having a delicate rose or purple tint. 
Quartz crystals, some of them exhibiting interesting forms and often 
associated with sulphate of barytes and calcareous spar, occur on the 
banks of Vrooman and Laidlaw lakes. 
An important locality of feldspar is reported to exist on High Island 
in the St. Lawrence, opposite to Alexandria.* This substance is used 
♦ Emmons. N. Y. Geological Reports, 1837, p. 103, 
