Scientific American Supplement, No. 344, August 5, 1882

V >> Various >> Scientific American Supplement, No. 344, August 5, 1882

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I trust by the use of these distinguishing reactions one will be able
to recognize by the tables to be given the name of the mineral in hand,
especially as they are from certain parts, where all the minerals
occurring therein are known to us; and I have worded the characteristics
so that they will serve to isolate from all that possibly could be found
in that locality.

The first general locality is Bergen Hill, New Jersey. This comprises
the range of bluffs of trap rock commencing at Bergen Point and running
up behind Jersey City and Hoboken, etc., to the part opposite about
Thirtieth Street, New York, where it comes close to the river, and from
there along the river to the north for a long distance, known as the
Palisades. It is about a mile wide on an average, and from a few feet to
about two hundred feet in height. The mineralogical localities in and
upon it are at the following parts, commencing at the south: First
Pennsylvania Railroad cuts where the mining operations are just about
completed; then the Erie Tunnel, in which the specimens that first made
Bergen Hill noted as a mineralogical locality, and whose equals have not
since been procured, were found, but which is now inaccessible to the
general public. Further north is the Morris and Essex Tunnel, in which
many fine specimens were secured, and is also inaccessible; and last,
but far from being least, is the Ontario Tunnel at Weehawken; and, as
it is the only practicable part besides the Pennsylvania Railroad and a
number of surface outcrops which I will mention, I will commence with
that.

_The Weehawken Tunnel_--This tunnel is now being cut through the
trap-rock for the New York, Ontario, and Western Railroad, and will
be completed in a few months, but will, probably, be available as a
mineralogical locality for a year to come. It is located about half a
mile south of the Weehawken Ferry from Forty-second Street, New York
city, and the place where to climb upon the hill to get to the shafts
leading to it is made prominent by the large body of light-colored rock
on the dump, a few rods north of where the east entrance is to be. The
western end is in the village of New Durham, on the New Jersey Northern
Railroad, and recognized by the immense earth excavations. A pass is
necessary to gain admittance down the shafts, and this can be procured
from the office of the company, between the third and fourth shafts to
the tunnel, in the grocery and provision store just to the north of
the tramway connecting the shafts on the surface. As it will not be
necessary to go down in any of the shafts besides the first and second
in order to fulfill the objects of this paper, no difficulty need be
encountered in procuring the pass if this is stated.

These two shafts are about eight hundred feet apart and one hundred and
seventy feet deep. A platform elevator is the mode of access to the
tunneled portion below, and a free shower-bath is included in the
descent; consequently, a rubber-coat and water tight boots are
necessary. A pair of overalls should be worn if one is to engage in
any active exploration below; candles should also be provided, as the
electric lights, at the face of the headings, give but little light, and
remind one very forcibly of a dim flash light with a foliaged tree in
front of it. The electric wires for supplying these arrangements run
along the north side of the tunnel for those on the east headings, and
on the south side for the west. They are excellent things to keep clear
of, as they have sufficient current passing through them to knock one
down; thus their position can be readily ascertained.

_Modes of Occurrence of the Minerals_.--In general, the greater number
of the specimens which are to be found in the tunnel occur in veins
generally perpendicular, and with other minerals of little or no value,
as calcite, chlorite, and imperfect crystals of the same mineral. A
few occur in nodules inclosed in the solid body of rock, and in which
condition they are seldom of value. The greater abundance are in the
veins of the dark-green soft chlorite, and some few in horizontal beds.
The minerals are found in the first condition by examining all the veins
running from floor to ceiling of the tunnel. The ores of calcite first
mentioned are very conspicuous, they being white in the dense black
rock. They may be chipped from, as there are about thirty or forty of
them exposed in each shaft, and the character of the minerals examined
to see if anything but calcite is in it. This is ascertained by a drop
of acid, as explained before, and by the descriptions given further on.
The veins of chlorite are not so conspicuous, being of a dark-green
color; but by probing along the walls with a stick or hammer, they may
be recognized by their softness, or by its dull glistening appearance.
They are comparatively few, but from an inch to three feet wide; and
minerals are found by digging it out with a stick or a three-foot drill,
to be had at the headings. Where the most minerals occur in the chlorite
is when plenty of veins of calcite are in its vicinity, and its edges
near the trap are dry and crumbly. It is here where the minerals are
found in this crumbly chlorite, and generally in geodes--that is, the
faces of the minerals all point inward, formerly a spherical mass--rough
and uncouth on the outside, and from half an inch to nearly a foot in
diameter. These are valuable finds, and well worth digging for. The beds
of minerals generally are of but one species, and will be mentioned
under the head of the minerals occurring in them. Besides, in the tunnel
there are generally more or less perfect minerals upon the main dump
over the edge of the bluff toward the river. Here many specimens that
have escaped the eyes of the miners may be found among the loose rock,
being constantly strewn out by the incline of the bed; in fact, this is
the only place in which quite a number of the incident minerals may be
found; but I will not linger longer on this, as I shall refer to it
under the minerals individually.

The minerals occurring at the tunnel are as follows, with their
descriptions and locations in the order of their greatest abundance:

_Calcite_.--This mineral occurs in great abundance in and about the
tunnel, and from all the shafts. There are two forms occurring there,
the most abundant of which is the rhombohedral, after Fig. 3. It can
generally be obtained, however, in excellent crystals, which, although
perfect in form, are opaque, but often large and beautiful. It is always
packed with a thousand or its multiple of other crystals into veins of a
few inches thick; and crystals are obtained by carefully breaking with
edge of the cold chisel these masses down to the fundamental form shown.
As the masses are never secured by the miners, they can always be picked
from the piles of _debris_ around the shafts and the dumps, and afford
some little instruction as to the manner in which a mineral is built up
by crystallization, and may be subdivided by cleavage to a crystal of
the same shape exactly, but infinitesimally small. A crystal to be worth
preserving should be about an inch in diameter, and as transparent as is
attainable.

Another form of calcite which is to be sparingly found is what is called
dogtooth spar, having the form shown in Fig. 4. They occur in clear
wine-yellow-colored crystals, from a quarter to half an inch in length;
they occur in the chlorite in geodes of variable sizes, but generally
two and a half inches in diameter, and which, when carefully broken in
half, showed beautiful grottoes of these crystals. The few of these that
I have found were in the four-foot vein of chlorite down the Shaft No.
1, to the west of the shaft about one hundred and fifty feet, and on
the south wall; it may be readily found by probing for it, and then the
geodes by digging in. There need be no difficulty in finding this vein
if these conditions are carefully considered, or if one of the miners
be asked as to the soft vein. Both these forms of calcite may be
distinguished from the other minerals by first effervescing on coming
in contact with the acids; second, by glowing with an intense (almost
unbearably so) light when heated with the blowpipe, but not fusing.
Their specific gravity is 2.6, or near it, and hardness about 3, or
equal to ordinary unpolished white marble.

_Natrolite_.--The finest specimens of this mineral that have ever been
found in Bergen Hill were taken from a bed of it in this tunnel, having
in its original form, before it was cut out by the tunnel passing
through, over one hundred square feet, and from one-half to two and a
half and even three inches in thickness; it was in all possible shapes
and forms--all extremely rare and beautiful. A large part of one end
of this bed still remains, and, by careful cutting, fine masses may be
obtained. This bed may be readily found; it is nearly horizontal, and in
its center about four feet from the floor of the tunnel, and about half
an inch thick. It is down Shaft No. 2, on the north wall, and commences
about eighty feet from the shaft. It is cut into in some places, but
there is plenty more left, and can be obtained by cutting the rock
above it and easing it out by means of the blade of a knife or similar
instrument. This natrolite is a grouping of very small but perfect
crystals, having the forms shown in Fig. 5; they are from a quarter to
an inch long, and, if not perfectly transparent, are of a pure white
color; they may be readily recognized by their form, and occurring in
this bed. Its hardness, which is seldom to be ascertained owing to the
delicacy of the crystals, is about 5, and the specific gravity 2.2.
This is readily found, but is no distinction; its reaction before the
blowpipe, however, is characteristic, it readily fusing to a transparent
globule, clear and glassy, and by forming a jelly when heated with
acids. The bed holding the upright crystals is also natrolite in
confused matted masses. This mineral has also been found in other parts
of the shaft, but only in small druses. There is a prospect at present
that another bed will be uncovered soon, and some more fine specimens to
be easily obtained.

_Pectolite_, or as it is termed by the miners, "silky spar."--This
mineral is quite abundant and in fine masses, not of the great beauty
and size of those taken from the Erie Tunnel, but still of great
uniqueness. The mineral is recognized by its peculiar appearance, as
is shown in Fig. 6, where it may be seen that it is in groups of
fine delicate fibers about an inch long, diverging from a point into
fan-shaped groups. The fibers are very tightly packed together, as are
also the groups; they are very tough individually, and have a hardness
of 4, and a specific gravity of about 2.5. It gelatinizes on boiling
with acid, and a fragment may be readily fused in the blowpipe flame,
yielding a transparent globule. The appearance is the most striking
characteristic, and at once distinguishes this mineral from any of the
others occurring in this locality. Considerable quantities of pectolite
may generally be found on the dump, but also in Shaft No. 1, and
especially No. 2. The veins of it are difficult to distinguish from the
calcite, as they are almost identical in color, and many of the calcite
veins are partly of pectolite--in fact, every third or fourth vein will
contain more or less of it. There is, however, a very fine vein of
pectolite about twenty-five feet further east from the natrolite bed; it
runs from the floor to ceiling, and is about two inches in thickness;
some specimens of which I took from these were unusually unique in both
size and appearance. It makes a very handsome specimen for the cabinet,
and should be carefully trimmed to show the characteristics of the
mineral.

_Datholite_.--This mineral has been found very frequently in the tunnel,
it occurring in pockets in the softer trap near the chlorite, and also
in the latter, generally at a depth of one hundred and fifty feet from
the surface, and consequently near the ceiling of the tunnel. All that
has been found of any great beauty has been in the western end of the
Shaft No. 1 and the eastern of Shaft No. 2, where the trap is quite
soft; here it is found nearly every day in greater or less quantity, and
from this some may generally be found on the dump, or, in the vein
of chlorite which I mentioned as a locality for the dogtooth spar,
considerable may be obtained in it and on its western edge near the
ceiling. A ladder about thirteen feet long is used for attending the
lights, and may generally be borrowed, and access to the remainder
of this pocket thus gained. Datholite is also very characteristic in
appearance, and can only be confounded with some forms of calcite
occurring near it. It occurs in small glassy, nearly globular crystals;
they are generally not over three-sixteenths of an inch in diameter, and
generally pure and perfectly transparent, having a hardness of a little
over 5, and specific gravity of 3; as it generally occurs as a druse
upon the trap, or an apopholite, calcite, etc., this is seldom
attainable, however, and we have a very distinctive characteristic in
another test: this is the blowpipe, under which it at first intumesces
and then fuses to a transparent globule, and the flame, after playing
upon it, is of a deep green color. Nitric acid must be used to boil it
up with, and with it it may be readily gelatinized. This last test will
seldom be necessary, however, and may be dispensed with if the hardness
and blowpipe reactions may be ascertained.

_Apopholite_.--This beautiful mineral has been found in fair abundance
at times in Shafts No. 1 and 2 in pockets, and seldom in place, most of
it being taken from the loose stone at the mouth of the shaft, and it
may generally be found on the dump. It is readily mistaken for calcite
by the miners and those unskilled in mineralogy, but a drop of acid will
quickly show the difference. The sizes of the crystals are very various,
from an eighth of an inch long or thick, to, in one case, an inch and
a half. The colors have been varied from white to nearly all tints,
including pink, purple, blue, and green; the white variety is, however,
the most abundant, and makes a handsome cabinet specimen. The crystals
are generally packed together in a mass, but are frequently set apart as
heavy druses of crystals having the form shown in Fig. 7. Sometimes,
as in the former grouping, the crystals are without the pyramidal
terminations, and are then right square prisms. The fracture being at
perfect right angles, distinguishes it from calcite. Its hardness is
generally fully 5, the specific gravity between 2.4 and 2.5; it is
difficult to fuse before the blowpipe, but is finally fused into an
opaque globule. Upon heating with nitric acid it partly dissolves, and
the remainder becomes flaky and gelatinous. Apopholite, although quite
rare, now may be bought from the men, or at least one of the engineers
of Shaft No. 2's elevator, and generally at low terms.

_Phrenite_.--This mineral is quite abundant in Shafts No. 1 and 2, in
very small masses, incrustations, and even in small crystals. It
occurs embedded in or incrusting the trap, and also with calcite and
apopholite. The only sure place to find it is at the southwest side of
an opening through the pile of drift rock under the trestle work of the
tramway, between shaft No. 1 and the dump, and within a few feet of a
number of wooden vats sunk into the ground seen just before descending
the hills and near the edge. Here on a number of blocks of trap it may
be found, a greenish white incrustation about as thick as a knife blade;
it also may be found on the main dump, and is sometimes found in plates
one-eighth of an inch thick, of a darker green color, upon calcite. Its
easiest distinguishment from the other minerals of this locality, with
which it might be confounded, is its great hardness of from 6 to 7.
It is very fragile and brittle, however, and is never perfectly
transparent, but quite opaque; its specific gravity is 2.9, and it is
readily fused before the blowpipe after intumescing. It partly dissolves
in acid without gelatinizing, leaving a flaky residue; it is a beautiful
mineral when in masses or crystals of a dark green color, but the best
place in the vicinity to secure specimens of this kind is, as I will
detail hereafter, at Paterson, N. J.

_Iron and Copper Pyrites_.--Both of these common but frequently
beautiful minerals occur in the tunnel and adjacent rocks in great
abundance. The crystals are generally about one-fourth of an inch in
diameter, and groups of these may be frequently obtained on the dump in
the shafts, especially No. 1 and 2, and where the rock is being cleared
away for the eastern entrance to the tunnel. They resemble each other
very much; the iron pyrites, however, is in cubical forms and having the
great hardness of from 6 to 7, while the copper pyrites, less abundant
and in forms having triangles for bases, but having sometimes other
forms and a hardness of but 3 to 4. Both are similar in aspect to a
piece of brass, and cannot be mistaken for any other mineral. The form
of the copper pyrites is shown in Fig. 8; the iron is, as before noted,
in cubes, more or less modified.

_Stilbite_.--Small quantities of this beautiful mineral have been found
in Shaft No. 2, in a small bed of but a few square feet in area, but
quite thick and appearing much like natrolite. This bed was about one
hundred feet east from Shaft No. 2, and in the center of the heading
when it was at that point. It has been encountered since in small
quantities, and it would do well to look out for it in the fresh
tunneled portion after the date appended to this paper. It generally
occurs in the form shown in Fig. 9, grouped very similarly to natrolite,
and being right upon the rock or a thin bed of itself. The crystals are
generally half an inch long, but often less. The modifications of the
above form, which are frequent in this species, strike one forcibly of
the resemblance they bear to a broad stone spear head on a diminutive
scale, with a blunted edge; their hardness is about 4, specific gravity
2.2, the color generally a pearly white or grayish. After a long
boiling with nitric acid it gelatinizes, but it foams up and fuses to a
transparent glass before the blowpipe. A little stilbite may often be
found on the dumps.

_Laumonite_ occurs in very small quantities on calcite or apopholite,
and can hardly be expected to be found on the trip; but as it might be
found, I will detail some of its characteristics. Hardness 4, specific
gravity 2.3; it generally occurs in small crystals, but more frequently
in a crumbly, chalky mass, which it becomes upon exposure to the air.
The crystals are generally transparent and frequently tinged yellow in
color. It gelatinizes by boiling with acid, and after intumescing before
the blowpipe, fuses to a frothy mass. To keep this mineral when in
crystals from crumbling upon exposure it may be dipped in a thin mastic
varnish or in a gum-arabic solution.

_Heulandite_.--This rare mineral has been found under the same
conditions as laumonite in Shaft No. 2, but it is seldom to be met with,
and then in small crystals. It is of a pure white color, sometimes
transparent. It intumesces and readily fuses before the blowpipe, and
dissolves in acid without gelatinizing. Hardness 4, specific gravity
2.2.

The few other minerals occurring in the tunnel are so extremly rare as
not to be met with by any other than an expert, and it is impossible
to detail the localities, as they generally occur as minute druses or
incrustations upon other minerals with which they may be confounded, and
have been removed as soon as discovered. The minerals referred to are
analcime, chabazite, Thompsonite, and finally, the mineral which I first
found in this formation, Hayesine, which is extremely rare, and of which
I only obtained sufficient to cover a square inch. The particulars in
regard to its locality, etc., maybe found in the _American Journal of
Sciences_ for June, page 458. I will now sum up the characteristics of
these several minerals of this locality in the table:

-------------------------------------------------------------------------------
| | | | | |
Name. | H. |Sp.|Action of |Action of |Color.|Appearance.
| |Gr.|Blowpipe. |hot acid. | |
----------+-----+---+-----------------+-----------------+------+---------------
| | | | | |
Calcite | 3 |2.6|Infusible, |Soluble with |White |Like Fig.
| | |but glows |effervescence | |3 and 4.
| | | | | |
Natrolite | 5 |2.2|Readily fused |Forms a jelly | do. |Like Fig 5.
| | |to clear globule | | |
| | | | | |
Pectolite | 4 |2.5| do. | do. do. | do. |Divergent
| | | | | |fibers, Fig. 6.
| | | | | |
Datholite | 5 |3.0|Intumesces, fused|Forms a jelly |Color-|Small, nearly
| | |to clear globule,| |less |spherical, etc.
| | |gives green flame| |white |
| | | | | |
Apopholite| 5 |2.5|Difficult, fused |Partly soluble |Tinted|Like Fig. 7.
| | |to opaque globule|in nitric acid | |
| | | | | |
Phrenite | 6 |2.9|Intomesces, fused|Partly soluble |Green-|In tables and
|to 7 | |to clear globule |in nitric acid, |ish |incrustations.
| | | |leaving flakes | |
| | | | | |
Iron | 6 |5.0|Burns and yields | |Brass |Cubical.
pyrites |to 7 | |a black globule, | | |
| | |decrepitates | | |
| | | | | |
Copper | 3 |4.2| do. do. | | do. |Tetrahedronal.
pyrites |to 4 | | | | |
| | | | | |
Stilbite | 4 |2.2|Intumesces and |Difficult; jelly |White |Like Fig. 8.
| | |fuses readily |on long boiling | |
| | | |with nitric acid.| |
| | | | | |
Laumonite | 4 |2.3|Intumesces and |Readily | do. |Generally
|to 0 | |fuses to frothy |gelatinizes | |chalky.
| | |mass | | |
| | | | | |
Heulandite| 4 |2.2|Intumesces and |Soluble, no | do. |In right
| | |readily fuses |jelly | |rhomboidal
| | | | | |prisms.
| | | | | |
-------------------------------------------------------------------------------

_To Distinguish the Minerals together the one from the other_.--Calcite
by effervescing on placing a drop of acid upon it. Natrolite resembles
stilbite, but may be distinguished by gelatinizing readily with
hydrochloric acid and by not intumescing when heated before the
blowpipe; from the other minerals by the form of the crystals and their
setting, also the locality in the tunnel in which it was found.

Pectolite sometimes resembles some of the others, but may be readily
distinguished by its _tough_ long fibers, not brittle like natrolite.
Datholite may generally be distinguished by the form of its crystals and
their glassy appearance, with great hardness, and by tingeing the flame
from the blowpipe of a true green color. Apopholite is distinguished
from calcite, as noticed under that species, and from the others by its
form, difficult fusibility, and part solubility.

Phrenite is characterized by its hardness, greenish color, occurrence,
and action of acid. Iron pyrites is always known by its brassy metallic
aspect and great hardness. Copper pyrites, by its aspect from the other
minerals, and from iron pyrites by its inferior hardness and less
gravity.

Stilbite is characterized by its form, difficult gelatinizing, and
intumescence before the blowpipe; from natrolite as mentioned under that
species.

Laumonite is known by its generally chalky appearance and a probable
failure in finding it.

Heulandite is distinguished from stilbite by its crystals and perfect
solubility; from apopholite by form of crystals.

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