Brucite.--This mineral occurs here in fair abundance, it being one of the principal localities for it in the United States, and where formerly extremely unique specimens were to be obtained. It has been pretty well exhausted, however, and the fine specimens are only to be obtained by digging into the veins of it in the rock, which are quite abundant on the south end of the walk, and, as I before noted, as deep as possible from the top of the veins, as it is a closely packed mineral not occurring in geodes, druses, etc. Two forms of it occur; the one, nemalite, is in fibers of a white to brown color resembling asbestos, but the fibers are brittle, and hardly as fine as a typical asbestos. It is packed in masses resembling the brucite, from which it only differs in breaking into fibers instead of plates, as I have explained in my description of that species (see Part II). They are both readily soluble in acids, with effervescence, and infusible but crumble to powder before the blowpipe, or at least become brittle; when rubbed in mass with a piece of iron, they phosphoresce with a yellow light; specific gravity, 2.4, hardness, 1.5 to 2. Its ready solubility in acids without effervescence at once distinguishes it from any mineral that it may resemble. The specimens of nemalite may be more readily obtained than the brucite but fine specimens of both may be obtained after finding a vein of it, by cutting away the rock, which is not hard to do, as it is in layers and masses packed together, and which maybe wedged out in large masses at a time with the cold chisel and hammer, perhaps at the rate of three or four cubic feet an hour for the first hour, and in rapidly decreasing rate as progress is made toward the unweathered rock and untouched brucite, etc.
Serpentine.--Fair specimens of this may be obtained of a dark oil green color, but not translucent or peculiarly perfect forms. The variety known as marmolite, which splits into thin leaves, is plentiful and often well worth removing.
Chromic Iron.--Crystals of this are included in the denser rock in great abundance; they are very small, seldom over a few lines in diameter, of an iron black color, of a regular octahedral form; sometimes large crystals may be found in place or in the disintegrated loose rock. I have seen them a half inch in diameter, and a half dozen in a small mass, thus forming an excellent cabinet specimen. By finding out by observation where they are the thickest in the rock, and cutting in at this point, more or less fine crystals may be obtained. This is readily found where they are so very abundant, near the equidistant points of the walk, that no difficulty should be encountered in so doing. These characteristics are interesting, and if large specimens cannot be obtained, any quantity of the small crystals may be split out, and, as a group, used for a representative at least. Before the blowpipe it is infusible, but if powdered, it slowly dissolves in the molten borax bead and yields a beautiful green globule. The specific gravity, which is generally unattainable, is about 4.5, and hardness 5 to 6. Its powder or small fragments are attracted by the magnet. A few small veins of this mineral are also to be found horizontally in the rock, and small masses may be obtained. They are very rare, however. I have seen numerous agates from this locality, but have not found them there myself. They may be looked for in the loose earth over the outcrop, or along the wall of the river. Our next locality is Paterson, N. J., or rather in a trip first to West Paterson by the D.L. & W. Railroad, Boonton branch, then back to Paterson proper, which is but a short distance, and then home by the Erie road, or, if an excursion ticket has been bought, on the D.L. & W, back from West Paterson. Garret Rock holds the minerals of Paterson, and although they are few in number, are very unique. The first is phrenite. This beautiful mineral occurs in geodes, or veins of them, near the surface of the basalt, which is the characteristic formation here, and lies on the red sandstone.
These veins are but two or three feet from the surface, and the ones from which the fine specimens are to be and have been obtained are exposed by the railroad cutting about a thousand feet north of the station at West Paterson, and on the west side of the rails. Near or below the beds is a small pile of debris, prominent by being the only one in the vicinity near the rails. In this loose rock and the veins which are by this description readily found and identified, they are about three inches in thickness, and in some places widen out into pockets even a foot in diameter They look like seams of a dark earth, with blotches of white or green matter where they are weathered, but are fresher in appearance inside. The rock, in the immediate vicinity of the veins, is soft, and may be readily broken out with the hammer of, if possible, a pick bar, and thus some of these geode cavities broken into, and much finer specimens obtained than in the vein proper. Considerable occurs scattered about in the before-mentioned pile of loose rock and debris, and if one does not prize it sufficiently to cut into the rock, taking the chances of lucky find, plenty may be obtained thus; but as it has been pretty thoroughly picked over where loose, it is much more satisfactory to obtain the fine specimens in place in the rock. When the bed for the railroad was being cut here, many fine specimens were obtained by those in the vicinity, and the natives of the place have it in abundance, and it may be obtained from many of them for a trifle, if one is not inclined to work it out. The mineral itself occurs in masses in the vein of a white, greenish white, or more or less dark green color. Sometimes yellowish crystals of it occur plentifully in short thick prisms, but the common form is that of round coralloid bunches, having a radiated structure within. Sometimes it is in masses made up of a structure resembling the leaves of a book slightly opened, and in nearly every shape and size. Crystals of the various forms may be well secured, and also the different colors from the deep green to the blue white, always remembering that true, perfect crystals are of more value than masses or attempted forms. The specific gravity is 2.8 to 2.9, hardness nearly 7 before the blowpipe; it readily fuses after intumescing; it dissolves in hot acid without gelatinizing, leaving a flaky residue.
Datholite.--This mineral is very abundant as inferior specimens, and frequently very fine ones may be obtained. They occur all around Garret Rock at the juncture of the basalt and red sandstone, in pockets, and as heavy druses. They are most abundant near the rock cuttings between West Paterson and Paterson, and may be cut out by patient labor. This is a long known and somewhat noted locality for datholite, and no difficulty need be experienced in obtaining plenty of fair specimens. Near them is the red sandstone, lying under the basalt, and baked to a scoriaceous cinder. Upon this is a layer of datholite in the form of a crystalline plate, and over or above this, either in the basalt or hanging down into cavities in the sandstone, are the crystals or geodes of datholite. Old spots are generally exhausted, and consequently every new comer has to hunt up new pockets, but as this is readily done, I will not expend further comment on the matter. The datholite, as in other localities, consists of groups of small colorless crystals. Hardness, about 5; specific gravity, 3. Before the blowpipe it intumesces and melts to a glassy globule coloring the flame green, and forms a jelly when boiled with the acids.
Pectolite--This mineral is also quite abundant in places, the greater part occurring with or near the phrenite before mentioned, in small masses generally more or less weathered, but in very fair specimens, which are about an inch in thickness. It is readily recognized by its peculiar appearance, which, I may again repeat, is in fibrous masses, these fibers being set together in radiated forms, and are quite tough and flexible, of a white color, and readily fused to a globule before the blowpipe.
Feldspar.--This mineral occurs strewn over the hill from place to place, and is peculiarly characterized by its lively flesh red color, quite different from the dull yellowish gray of that from Staten Island or Bergen Hill. Fine crystals of it are rather rare, but beautiful specimens of broken groups may be obtained in loose debris around the hill and in its center. I have not been able to locate the vein or veins from which it has come, but persistent search will probably reveal it, or it may be stumbled upon by accident. Some of the residents of the vicinity have some fine specimens, and it is possible that they can direct to a plentiful locality. However, some specimens are well worth a thorough search, and possess considerable value as mineralogieal specimens. The specific gravity of the mineral is 2.6, and it has a hardness of 6 before the blowpipe. It is with difficulty fused to a globule, more or less transparent. It occurs undoubtedly in veins in the basalt and near the surface of the outcrop As this locality has never before been mentioned as affording this species, it is fresh to the amateur and other mineralogists, and there need be no difficulty in obtaining some fine specimens. Its brilliant color distinguishes it from other minerals of the locality.
It is possible that some of the other zeolites as mentioned under Bergen Hill occur here, but I have not been able to find them. The reason may be that the rock is but little cut into, and consequently no new unaltered veins are exposed.
COPPER MINES, ARLINGTON, N. J.--A short distance north of this station, on the New York and Greenwood Lake Railroad, and about nine miles from Jersey City, is one of the cuttings into the deposits of copper which permeate many portions of the red sandstone of this and the allied districts in Connecticut and Massachusetts, and which have been so extensively worked further south at Somerville and New Brunswick, etc. There are quite a variety of copper minerals occurring in these mines, and as they differ but little in anything but abundance, I will describe this, the one nearest to New York City, as I promised in commencing these papers. The locality of this mine may be readily found, as it is near the old turnpike from Jersey City, along which the water-pipes or aqueduct, are laid. By taking the road directly opposite to the station at Arlington, walking north to its end, which is a short distance, then turning to the left along the road, there crossing and turning north up the next road joining this, until the turnpike is reached; this is then followed east for about a quarter-mile, passing occasional heaps in the road of green earth, until the head of a descent is reached, when we turn off into the field to the left, and there find the mine near the heaps of greenish rocks and ore scattered about, a distance from the station of about a mile and a half through a pleasing country. The entrance to the mine is to the right of the bank of white earth on the edge of, and in the east side of the hill; it is a tunnel more or less caved in, running in under the heaps of rock for some distance. It will not be necessary, even if it were safe, to venture into the mine, but all the specimens mentioned below may be obtained from the heaps of ore and rock outside, and in the outcrops in the east side of the hill, a little north of the mouth of the tunnel to the mine. The hammer and cold chisel will be necessary, and about three hours should be allowed to stay, taking the noon train from New York there, and the 5.09 P.M. train in return, or the 6.30 A.M. train from the city, and the 1.57 P.M. in return. This will give ample opportunity for the selection of specimens, and, if time is left, to visit the water works, etc.
Green Malachite.--This is the prominent mineral of the locality, and is conspicuous by its rich green color on all the rocks and in the outcrops. Fine specimens of it form excellent cabinet specimens. It should be in masses of good size, with a silky, divergent, fibrous structure, quite hard, and of a pure oil green color, for this purpose. Drused crystals of it are also very beautiful and abundant, but very minute. As the greater part of it is but a sixteenth or eighth of an inch in thickness, it may require some searching to secure large masses a quarter to a half-inch in thickness, but there was considerable, both in the rock, debris, and outcrop, remaining the last visit I made to the place a few months ago. The mineral is so characterized by its color and solubility in acid that a detailed description of it is unnecessary to serve to distinguish it. Its specific gravity is 4, and hardness about 4. It decrepitates before the blowpipe, but when fused with some borax in a small hollow on a piece of wood charcoal, gives a globule of copper. It readily dissolves in acids, with effervescence, as it is a carbonate of copper.