Scientific American Supplement No. 822 by Various

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A GEM-BEARING GRANITE VEIN IN WESTERN CONNECTICUT.

By L.P. GRATACAP.

In the county of Litchfield, Conn., in the midst of some of the most
attractive hill country of that region, a very striking mineral
fissure has been opened by Mr. S.L. Wilson, which, in both its
scientific and commercial aspects, is equally important and
interesting. It is a broad crevice, widened at the point of excavation
into something like a pocket and filled, between its inclosing walls
of gneiss, with a granitic mass whose elements have crystallized
separately, so that an almost complete mineralogical separation has
been effected of quartz, mica, and feldspar, while associated
aggregates, as beryl and garnet, have formed under conditions that
make them valuable gem fabrics.

The vein has a strike south of west and north of east and a distinct
dip northwest, by which it is brought below the gneiss rock, which
forms an overhanging wall, on the northerly side of the granitic mass,
while on the southerly edge the same gneiss rock makes an almost
vertical foot wall, and exhibits a sharp surface of demarkation and
contact. The rock has been worked as an open cut through short lateral
"plunges," or tunnels have been used for purposes of exploration in
the upper part of its extent. Its greatest width appears to be
fifty-one feet, and the present exposure of its length three hundred.
It undergoes compression at its upper end, and its complete extinction
upon the surface of the country at that point seems probable. At its
lower end at the foot of the slope wherein the whole mass appears, it
reveals considerable development, and affords further opportunities
for examination, and, possibly, profitable investment. It has been
formed by a powerful thrust coincident with the crumpling of the
entire region, whereby deeply seated beds have become liquefied, and
the magma either forced outward through a longitudinal vent or brought
to the surface by a process of progressive fusion as the heated
complex rose through superincumbent strata dissipated by its entrance
and contributing their substance to its contents. The present exposure
of the vein has been produced by denudation, as the coarsely
crystalline and dismembered condition of the granite, with its large
individuals of garnet and beryl, and the dense, glassy texture of the
latter, indicate a process of slow cooling and complete separation,
and for this result the congealing magma must necessarily have been
sealed in by strata through which its heat was disseminated slowly.

For upon the most cursory inspection of the vein, the eye is arrested
at once by the large masses of crystalline orthoclase, the heavy beds
of a gray, brecciated quartz and the zones and columns of large leaved
mica. It was to secure the latter that Mr. Wilson first exploited this
locality, and only latterly have the more precious contents of the
vein imparted to it a new and more significant character. The mica,
called by Mr. Atwood, the superintendent of the work, "book mica,"
occurs in thick crystals, ranged heterogeneously together in stringers
and "chimneys," and brilliantly reflecting the sunlight from their
diversely commingled laminae. This mica yields stove sheets of about
two to three by four or five inches, and is of an excellent,
transparent quality. It seems to be a true muscovite, and is seldom
marred by magnetic markings or crystalline inclusions that would
interfere with its industrial use. Seams of decomposition occur, and a
yellowish scaly product, composed of hydrated mica flakes, fills them.
The mica does not everywhere present this coarsely crystalline
appearance, but in flexures and lines of union with the quartz and
orthoclase is degraded to a mica schist upon whose surfaces appear
uranates of lime and copper (autunite and torbernite), and in which
are inclosed garnet crystals of considerable size and beauty. The
enormous masses of clean feldspar made partially "graphic" by quartz
inclosures are a conspicuous feature of the mine. In one part of the
mine, wooden props support an overhanging ledge almost entirely
composed of feldspar, which underneath passes into the gray brecciated
quartz, which again grades into a white, more compact quartz rock. It
is in this gray brecciated quartz that the beryls are found. These
beautiful stones vary extremely in quality and color. Many of the
large crystals are opaque, extensively fractured, and irregular in
grain, but are found to inclose, especially at their centers, cores of
gem-making material.

The colors of the beryls grade from an almost colorless mineral
(goshenite) though faintly green, with blue reflections, yellowish
green of a peculiar oily liquidity (davidsonite), to honey yellows
which form the so-called "golden beryls" of the trade, and which have
a considerable value. These stones have a hardness of 8, and when cut
display much brilliancy. Many assume the true aquamarine tints, and
others seem to be almost identical with the "Diamond of the Rhine,"
which as early as the end of the fifteenth century was used as a
"fraudulent substitute for the true diamond" (King). Few, very few,
belong to the blue grades, and the best of these cannot compare with
those from Royalston, Mass. Those of amber and honey shades are
beautiful objects, and under artificial light have a fascination far
exceeding the olivine or chrysoberyl. These are not as frequent as the
paler varieties, but when found excite the admiration of visitor and
expert. It seems hardly probable that any true emeralds will be
uncovered and the yellow beryls may not increase in number. Their use
in the arts will be improved by combining them with other stones and
by preparing the larger specimens for single stone rings.

Very effective combinations of the aquamarine and blue species with
the yellow may be recommended. Tourmaline appears in some quantity,
forming almost a schist at some points, but no specimens of any value
have been extracted, the color being uniformly black. The garnets are
large trapezohedral-faced crystals of an intense color, but penetrated
with rifts and flaws. Many, no doubt, will afford serviceable gem
material, but their resources have not yet been tested by the
lapidary.

While granite considered as a building stone presents a complex of
quartz, mica, and feldspar so confusedly intercrystallized as to make
a homogeneous composite, in the present mass, like the larger and
similar developments in North Carolina, these elements have excluded
each other in their crystallization, and are found as three separate
groups only sparingly intermingled. The proportions of the constituent
minerals which form granite, according to Prof. Phillips, are twenty
parts of potash feldspar (orthoclase), five parts of quartz, and two
parts of potash mica (muscovite), and a survey of Mr. Wilson's quarry
exhibits these approximate relations with surprising force.

There can be but little doubt that this vein is a capital example of
hydrothermal fusion, whereby in original gneissic strata, at a
moderate temperature and considerable depth, through the action of
contained water, with the physical accompaniment of plication, a
solution of the country rock has been accomplished. And the cooling
and recrystallization has gone on so slowly that the elements of
granite have preserved a physical isolation, while the associated
silicates formed in the midst of this magma have attained a supremely
close and compact texture, owing to the favorable conditions of slow
growth giving them gem consistencies. The further development of the
vein may reveal interesting facts, and especially the following
downward of the rock mass, which we suspect will contract into a
narrower vein. At present the order of crystallization and separation
of the mineralogical units seems to have been feldspar, mica, garnet,
beryl, quartz.

In the artificial preparation of crystals it is invariably found that
perfect and symmetrical crystals, and crystals of large size, are
produced by slow, undisturbed cooling of solutions; the quiet
accretion permits complete molecular freedom and the crystal is built
up with precision. Nor is this all. In mixtures of chemical compounds
it is presumable that the separate factors will disengage themselves
from each other more and more completely, and form in purer masses as
the congelation is slowly carried on. A sort of concretionary affinity
comes into play, and the different chemical units congregate together.
At least such has been the case in the granitic magma of which Mr.
Wilson now possesses the solidified results. The feldspar, the quartz,
the mica, have approximately excluded each other, and appear side by
side in unmixed purity. And does it not seem probable that this
deliberate process of solidification has produced in the beryls, found
in the center of the vein at the points of slowest radiation, the
glassy gem texture which now makes them available for the purposes of
art and decoration?

* * * * *

THE STUDY OF MANKIND.

Professor Max Muller, who presided over the Anthropological Section of
the British Association, said that if one tried to recall what
anthropology was in 1847, and then considered what it was now, its
progress seemed most marvelous. These last fifty years had been an age
of discovery in Africa, Central Asia, America, Polynesia, and
Australia, such as could hardly be matched in any previous century.
But what seemed to him even more important than the mere increase of
material was the new spirit in which anthropology had been studied
during the last generation. He did not depreciate the labors of
so-called dilettanti, who were after all lovers of knowledge, and in a
study such as that of anthropology, the labors of these volunteers, or
franc-tireurs, had often proved most valuable. But the study of man in
every part of the world had ceased to be a subject for curiosity only.
It had been raised to the dignity and also the responsibility of a
real science, and was now guided by principles as strict and rigorous
as any other science. Many theories which were very popular fifty
years ago were now completely exploded; nay, some of the very
principles by which the science was then guided had been discarded.
Among all serious students, whether physiologists or philologists, it
was by this time recognized that the divorce between ethnology and
philology, granted if only for incompatibility of temper, had been
productive of nothing but good.

CLASSIFICATION.

Instead of attempting to classify mankind as a whole, students were
now engaged in classifying skulls, hair, teeth, and skin. Many solid
results had been secured by these special researches; but as yet, no
two classifications, based on these characteristics, had been made to
run parallel. The most natural classification was, no doubt, that
according to the color of the skin. This gave us a black, a brown, a
yellow, a red, and a white race, with several subdivisions. This
classification had often been despised as unscientific; but might
still turn out far more valuable than at present supposed. The next
classification was that by the color of the eyes, as black, brown,
hazel, gray, and blue. This subject had also attracted much attention
of late, and, within certain limits, the results have proved very
valuable. The most favorite classification, however, had always been
that according to the skulls. The skull, as the shell of the brain,
had by many students been supposed to betray something of the
spiritual essence of man; and who could doubt that the general
features of the skull, if taken in large averages, did correspond to
the general features of human character? We had only to look around to
see men with heads like a cannon ball and others with heads like a
hawk. This distinction had formed the foundation for a more scientific
classification into brachycephalic, dolichocephalic, and mesocephalic
skulls. If we examined any large collection of skulls we had not much
difficulty in arranging them under these three classes; but if, after
we had done this, we looked at the nationality of each skull, we found
the most hopeless confusion. Pruner Vey, as Peschel told us in his
"Volkerkunde," had observed brachycephalic and dolichocephalic skulls
in children born of the same mother; and if we consider how many women
had been carried away into captivity by Mongolians in their inroads
into China, India, and Germany, we could not feel surprised if we
found some long heads among the round heads of those Central Asiatic
hordes.

DIFFERENCES IN SKULLS.

Only we must not adopt the easy expedient of certain anthropologists
who, when they found dolichocephalic and brachycephalic skulls in the
same tomb, at once jump to the conclusion that they must have belonged
to two different races. When, for instance, two dolichocephalic and
three brachycephalic skulls were discovered in the same tomb at
Alexanderpol, we were told at once that this proved nothing as to the
simultaneous occurrence of different skulls in the same family; nay,
that it proved the very contrary of what it might seem to prove. It
was clear, we were assured, that the two dolichocephalic skulls
belonged to Aryan chiefs and the three brachycephalic skulls to their
non-Aryan slaves, who were killed and buried with their masters,
according to a custom well known to Herodotus. This sounded very
learned, but was it really quite straightforward? Besides the general
division of skulls into dolichocephalic, brachycephalic, and
mesocephalic, other divisions had been undertaken, according to the
height of the skull, and again according to the maxillary and the
facial angles. This latter division gave us orthognatic, prognathic,
and mesognathic skulls. Lastly, according to the peculiar character of
the hair, we might distinguish two great divisions, the people with
woolly hair (Ulotriches) and people with smooth hair (Lissotriches).
The former were subdivided into Lophocomi, people with tufts of hair,
and Eriocomi, or people with fleecy hair. The latter were divided into
Euthycomi, straight haired, and Euplocomi, wavy haired. It had been
shown that these peculiarities of the hair depended on the peculiar
form of the hair tubes, which in cross sections were found to be
either round or elongated in different ways. All these classifications,
to which several more might be added, those according to the orbits of
the eyes, the outlines of the nose, and the width of the pelvis, were
by themselves extremely useful. But few of them only, if any, ran
strictly parallel. Now let them consider whether there could be any
organic connection between the shape of the skull, the facial angle,
the conformation of the hair, or the color of the skin on one side,
and what we called the great families of language on the other.

CONNECTION OF LANGUAGE AND PHYSICAL CONFORMATION.

That we spoke at all might rightly be called a work of nature, _opera
naturale_, as Dante said long ago; but that we spoke thus or thus,
_cosi o cosi_, that, as the same Dante said, depended on our
pleasure--that was our work. To imagine, therefore, that as a matter
of necessity, or as a matter of fact, dolichocephalic skulls had
anything to do with Aryan, mesophalic with Semitic, or brachycephalic
with Turanian speech, was nothing but the wildest random thought. It
could convey no rational meaning whatever; we might as well say that
all painters were dolichocephalic, and all musicians brachycephalic,
or that all lophocomic tribes worked in gold, and all lisocomic tribes
in silver. If anything must be ascribed to prehistoric times, surely
the differentiation of the human skull, the human hair and the human
skin would have to be ascribed to that distant period. No one, he
believed, had ever maintained that a mesocephalic skull was split or
differentiated into a dolichocephalic and a brachycephalic variety in
the bright sunshine of history. Nevertheless, he had felt for years
that knowledge of languages must be considered in future as a _sine
qua non_ for every anthropologist. How few of the books in which we
trusted with regard to the characteristic peculiarities of savage
races had been written by men who had lived among them for ten or
twenty years, and who had learned their languages till they could
speak them as well as the natives themselves. It was no excuse to say
that any traveler who had eyes to see and ears to hear could form a
correct estimate of the doings and sayings of savage tribes.

TRAVELERS' IMPRESSIONS.

It was not so, as anthropologists knew from sad experience. Suppose a
traveler came to a camp where he saw thousands of men and women
dancing round the image of a young bull. Suppose that the dancers were
all stark naked, that after a time they began to fight, and that at
the end of their orgies there were three thousand corpses lying about
weltering in their blood. Would not a casual traveler have described
such savages as worse than the negroes of Dahomey? Yet these savages
were really the Jews, the chosen people of God. The image was the
golden calf, the priest was Aaron, and the chief who ordered the
massacre was Moses. We might read the 32d chapter of Exodus in a very
different sense. A traveler who could have conversed with Aaron and
Moses might have understood the causes of the revolt and the necessity
of the massacre. But without this power of interrogation and mutual
explanation, no travelers, however graphic and amusing their stories
might be, could be trusted; no statements of theirs could be used by
the anthropologist for truly scientific purposes. If anthropology was
to maintain its high position as a real science, its alliance with
linguistic studies could not be too close. Its weakest points had
always been those where it trusted to the statements of authorities
ignorant of language and of the science of language. Its greatest
triumphs had been achieved by men such as Dr. Hahn, Bishops Callaway
and Colenso, Dr. W. Gill and last, not least, Mr. Man, who had
combined the minute accuracy of the scholar with the comprehensive
grasp of the anthropologist, and were thus enabled to use the key of
language to unlock the perplexities of savage customs, savage laws and
legends, and, particularly, of savage religions and mythologies. If
this alliance between anthropology and philology became real, then,
and then only, might we hope to see Bunsen's prophecy fulfilled, that
anthropology would become the highest branch of that science for which
the British Association was instituted.

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