Mineral Industries and Geology of Certain Areas - Vermont Agency ...

38 REPORT OF THE VERMONT STATE GEOLOGIST.
and vary from a maximum length, as at present exposed, of
three-fourths of an inch down to not more than one-sixteenth.
of an inch. The variety is similar in all respects to the Canadian
product, but it is met only in the prospects owned by Mr.
Tucker at Tucker's Mill and near Lowell. The second variety
of asbestos is what, for lack of a better name, I will call ' slipfiber,'
because it occurs upon the slickensided surfaces that are
common to this exposure of serpentine just as to all others the
world over. These fibers form layers of varying thickness,
seldom more than a quarter of an inch, but as they run parallel
to the slickensided surfaces they may themselves be of various
lengths, from a fraction of an inch tip to 3 or 4 inches. The
fiber is coarser than that of the veins, and will not furnish sc
good a grade. At the same time it occurs in larger quantity.
This is the variety of fiber which will be produced by the New
England and the National companies. It also appears in a
minor degree in the other openings.
There is little doubt that the region will become commerciallv
productive, and that very considerable amounts of
asbestos will he contributed by it to the markets. It is possible
that in time larger veins may be discovered which will give the
first grade, but at present all estimations of value should be
based upon a product of second and third grade. Under
present conditions there seems to be an excellent opportunity
for these to prove remunerative. The serpentine belts, as
shown by the geological survey of Vermont, run for great distances
to the north, and while it is impossible at this time to
report other definite discoveries, the area within which the geological
formations are favorable for the occurrence of asbestos
appears to be considerable. At the same time, the existence of
serpentine does not necessarily imply the presence of asbestos.
Even in the belt on Belvidere Mountain the fiber is sharply
limited to restricted localities. Although the serpentine has
been somewhat carefully searched already, and was in large part
traversed by the writer, in company with Mr. Tucker, vet no
other exposures were observed which appeared to be anything
ME
REPORT OF THE VERMONT STATE GEOLOGIsT. 39
like as favorable as the ones which have been opened. In many
ledges no fiber appeared at all."
While the existence of asbestos on and near Belvidere Mountain
has long been known, it was not until in 1899, when Mr.
Melvin E. Tucker, who has extensive lumber interest in the
region, gave his attention to the development of the mineral,
that the extent and value of the asbestos bearing serpentine
was realized. I have carefully examined the serpentine shoulder
of the mountain, and I think that the asbestos is more widely
distributed than would be indicated by Professor Kemp's last
paragraph.
In a report of one of the meetings of the New York Academy
21, 1901,*
of Sciences, October
Professor Kemp is quoted as
saying: " The serpentine seems to have been derived from
enstatite, cliallage and probably olivine, since unaltered nuclei
of these minerals are found in it. * * * It is difficult with
the data in hand, * * to trace the geological history of
the serpentine, but it must have been originally either an igneous
pyroxenite or peridotite or else a richly magnesian siliceous limestone.
There are such slight traces of
ca l cium_bearing minerals,
however, that the former supposition has greater weight. The
hornblende-Schist consists in largest part of commOil green
hornblende, but one may also observe epidote, zoisite and some
minor accessories."
The South Duxhury locality is also in many respects very
promising. The asbestos here is of the same chrysotile variety
as that at Belvidere Mountain. So far as I could judge from
surface indications and an examination of the few places where
small blasts have been made, the quality is quite as good, and
I should think the chance of obtaining long fiber better.
We find here a serpentine ledge which extends from South
Duxbury southward over the line into Moretown. The general
trend of the ridge is nearly north and south, being a little east
of south at the south end. I should estimate the length of
the ridge at about two hundred rodis, and its width at an averae
Science, vol. XIV, p. 773.