346 
MINING GEOLOGY 
North Carolina Geological Survey during the past year relating 
to the iron reserves of the state was the question of improved 
ore treatment, the hope being that large bodies of iron ore now 
undeveloped because of their location might be made available 
for market. 
As described by Dr. W. S. Bayley, who lately undertook for the 
Survey a special inquiry into the genetic relations of the ores 
in question the large open-cut walls of the Cranberry Mine pre¬ 
sent most excellent illustrations of the several phases of vein¬ 
filling and their relations one to another. “The magnetite is close¬ 
ly associated with the pegmatite. The miners declare that the 
richest ore is always near the pegmatite. Pegmatite and magme- 
tite veins both cut the lean ore, which is a mixture of hornblende 
and magnetite, and magnetite impregnations extend from the walls 
of the magnetite veins into the bordering rock, causing an enrich¬ 
ment of these, and giving rise to magnetite forms a constituent 
of coarse pegmatite, exactly as does feldspar, quartz, and horn¬ 
blende. It has the same shape as the other components, and the 
individual grains, when not aggregated, are of the same sizes 
as the grains of quartz, hornblende and feldspar. 
“More frequently the magnetite forms groups, either alone or 
with hornblende, and these constitute lenses in the pegmatite. 
There is a strong tendency for the hornblende and magnetite to 
occur together- They appear to be the last components to sep¬ 
arate, and often they occur in great masses forming lean ore 
deposits. Of the two perhaps magnetite is the later, since veins 
of this mineral penetrate the lean ore. It is probable^ however, 
that the magnetite separated at two stages, of which one was 
contemporaneous, or nearly so, with the great mass of hornblende, 
and the other was distinctly later. When the two minerals occur 
together in the lenses the hornblende is apt to occur on their bor¬ 
ders with the magnetite in their centers; and when arms extend 
into the surrounding quartz-feldspar mass the main portions of 
the lenses may be composed of magnetite or a mixture of mag¬ 
netite and hornblende, while the extensions consist entirely of 
hornblende. 
“There seems to be no question but that the ore of the Cran¬ 
berry deposit was made before the date (Jura-Trias) assigned 
to the intrusion of the Bakersville gabbro.” 
