3.

heat. A series of measurements on a number of these crystals proves them to belong to the hexagonal system, having in general the form shown in fig. 3. The average of forty-eight measurements of the prismatic angle is 119° 53', the six angles of the most perfect one found measuring as follows: 120° 30', 121° 6', 119° 12', 119° 6', 120° 36' and 120° 12'. The angle O 1 has been approximately determined to be about 136°, the roughness of the crystals rendering exact measurement extremely difficult. The pyra

4.

midal planes are sometimes entirely wanting, the crystal having only a basal termination. The base is often hollow, in one crystal presenting the appearance shown in fig. 4, the whole base being gone. The sides and bottom of this depression are quite rough, and show no attempt at regularity. Another termination is shown in fig. 5, where part of the base still remains: Fig. 3 was drawn under a power of 300 diameters, the general shape being retained, but the irregularities taken away. It is about 0.5 mm. in length and 0.06 mm. in diameter. The gold used in preparing these crystals should be pure and in a finely divided condition. I prefer gold precipitated from solution by ferrous sulphate, washed with dilute chlorohydric acid and then with water and dried. This should be treated with about twelve parts of mercury and well triturated in a mortar. The amalgam must then be heated to about 130° C., kept at that temperature for about five minutes, and then allowed to cool gradually. After this it should remain at rest for twelve hours or more. The amalgam, which should be quite fluid, is now to be digested in nitric acid, first of 12 sp. gr., and after of 14, heating very gently at the beginning, but toward the close of the operation raising it to boiling. The mass left undissolved consists of minute crystals resembling gold in color, but a little darker and having a greenish tinge. They are quite brittle and break with a slight touch. They contain about six per cent of mercury, which may be driven off without injuring the crystals by heating them for a short time to a dull red. The mass will then take the color of pure gold, becoming somewhat spongy, and lose entirely its brittle character. This process was patented in 1853, and used for some time in the preparation of gold for filling teeth, making what was called sponge or crystal gold. Hamilton College, April 4th, 1878.

5.

ART. IV.-On a new and remarkable mineral locality in Fairfield County, Connecticut; with a description of several new species occurring there; by GEORGE J. BRUSH and EDWARD S. DANA. First Paper.

Historical Note.

THE new locality of manganesian phosphates, which we shall describe in this and following papers, is situated near the village of Branchville, in the town of Redding, Fairfield County, Connecticut. Its remarkable character will be evident from the statement that we have thus far discovered, among the material which we have obtained from there, no less than six new and well defined species, besides many other known species of more or less rarity.

The locality was first opened some two years since by Mr. A. N. Fillow, upon whose land it is situated, and who made considerable excavations in the search for mica of commercial value. Only a limited quantity of this was obtained, so that the work was finally discontinued and the opening filled up; by which means the ledge was buried under six to eight feet of soil. With most commendable thoughtfulness, however, he laid aside and preserved a large number of specimens which seemed to him to be of some interest. In the latter part of the summer of 1877, Prof. Dana visited the region and his attention was called by Mr. Fillow to the collection of minerals mentioned, and by him several specimens were brought to New Haven. Later, Rev. John Dickinson of Redding, the adjoining village, happened to visit the locality and obtained a considerable amount of the minerals, some of which he sent to New Haven for determination. It was not, however, until the early spring of the present year that we were able personally to visit the locality. Appreciating then the unusual interest connected with it, we immediately inade arrangements with Mr. Fillow to uncover the ledge and to go forward with the exploration as thoroughly as possible. We have now pushed the matter as far as is practicable for the present, but later in the season we hope to accomplish more. The result of our work has been to place in our hands a large amount of material, in the examination of which we are at present engaged, and we are now ready to make public* a portion of the results. In addition to the material we have personally obtained, we have, through the liberality of Mr. Dickinson, come into the possession of a large number of additional specimens collected by

* Short notices of the new species eosphorite, triploidite, dickinsonite, and lithiophilite (by mistake printed lithiolite) were published on pp. 398, 481, of the preceding volume.

AM. JOUR. SCI.-THIRD SERIES, VOL. XVI, No. 91.-JULY, 1878.

himself before our first visits to Branchville. These have been of the greatest service to us in the study of the species occurring at the locality, and we would here express our great appreciation of his generosity. We would also mention our obligations to Mr. Fillow and his brother, who have been most careful in obtaining the best results possible in the explorations of which they have taken charge.

Brief general description.

All the minerals which we have obtained are from a single vein of albitic granite, and the line along which the explorations have been carried does not exceed twenty feet. The general description of the vein and of the minerals which compose it with the exception of the manganesian phosphates and the immediately associated species-we reserve for a later paper; we will mention, however, that outside of these we have identified the following species:

Albite, quartz, microcline in large masses, a hydro-mica near damourite having a peculiar concentric spherical structure, spodumene in crystals weighing one to two hundred pounds, cymatolite as a result of the decomposition of spodumene crystals, sometimes nine inches in width, apatite, microlite (sp. gr.=6), columbite (sp. gr.=56), apatite, garnet, tourmaline and staurolite.

The manganesian phosphates and related minerals occur in nests imbedded in the albite. A single deposit yielded almost all the material obtained, it being probable that what came out as the result of our work was a part of the same body of minerals which Mr. Fillow had blasted into two years before. A second deposit will be mentioned later as having furnished the lithiophilite.

The minerals which form the mass of the first mentioned bed are:-Eosphorite, dickinsonite, triploidite and rhodochrosite. Of these, the first three are new and are described at length in this paper. These four minerals, together with quartz, occur associated in the most intimate manner possible, it being not at all unusual to find all of them in a single hand specimen. This is especially true of the three new minerals: the eosphorite is often found in crystals entirely imbedded in the dickinsonite, and again the finely disseminated plates of dickinsonite give a green color to much of the massive eosphorite. Quartz is also contained in much of the massive eosphorite, thus giving it a very anomalous appearance; it also forms the mass in which the triploidite crystals are imbedded-both these points are spoken of more particularly later. Quartz is also often associated with the rhodochrosite, that mineral being disseminated in crystalline grains through the

quartz, in which occasional brilliant cubes of pyrite are also imbedded.

In addition to the above minerals, as original constituents of the same deposit, are amblygonite (hebronite), and a phosphate of manganese isomorphous with scorodite which we shall describe under the name reddingite. As secondary products we have apatite and quartz coating together crystals of eosphorite, vivianite in thin layers and crystals, besides other species, which as yet, owing to lack of sufficient material for examination, we have been unable to determine.

Furthermore, there are a variety of alteration products: each one of the manganesian phosphates yields on alteration a black or purple phosphate of manganese and iron sesquioxides, and the rhodochrosite gives a pseudomorph of hydrated oxides.

The second smaller nest discovered consisted almost exclusively of lithiophilite. Of the previously mentioned minerals rhodochrosite is the only one we have observed with it, and that occurs very sparingly. In addition, however, a peculiar green manganiferous apatite, spodumene and cymatolite are intimately associated with the lithiophilite, besides the black phosphate produced from its oxidation, and occasional crystals of uraninite and both green and yellow hydrated phosphates of uranium.

From the large amount of black oxidized material, rich in lithia, found with the first deposit it is probable that lithiophilite, or some other similar mineral of the triphylite group, formed one of the original constituents of that mass. In fact it was the discovery of lithia in the black product of decomposition, and its absence in eosphorite, triploidite and dickinsonite, which led us to make further search for the source of this alkali. Fortunately, in the deepest part of our explorations in the vein we struck a small nest which afforded us the fresh unaltered mineral.

We wish here to express our great obligations to Messrs. Samuel L. Penfield and Horace L. Wells of the Sheffield Laboratory, for the excellent analyses which their enthusiastic devotion to the work has enabled us to present in this paper. The carrying through of these analyses has involved in many cases more than usual difficulty, and we appreciate fully to what an extent the value of this article is dependent upon the skill and patient care with which these difficulties have been overcome.

1. EOSPHORITE.

General physical characters.-Eosphorite occurs in prismatic crystals, sometimes of considerable size, which belong to the orthorhombic system. They show a nearly perfect macrodiagonal cleavage. It also and more commonly occurs massive, some specimens showing the cleavage finely, but graduating into others which are closely compact. The hardness is 5. For the

specific gravity, three perfectly pure rose-colored specimens gave 3.124, 3.134 and 3·145; mean 3.134. The luster of crystallized specimens is vitreous to sub-resinous, upon cleavage surfaces exceedingly brilliant; of the massive mineral often greasy. The color of the crystals is pink, some having the bright shade common in rose-quartz, while others are paler and have a yellow to gray hue; the smallest crystals are nearly colorless. The massive compact mineral is pale pink, also grayish-, bluish-, and yellowish-white, and white. Some varieties closely resemble in color and luster green elæolite; the green color, however, is shown by the examination of thin sections under the microscope to be due to finely-disseminated scales of dickinsonite. Some varieties again are rendered impure by the presence of quartz through the mass, and they then have a whitish color and granular texture; this subject is expanded in a later paragraph.

The mineral is transparent to translucent. The streak is nearly white, and the fracture uneven to subconchoidal.

Description of crystals.-Specimens of crystallized eosphorite are rare. The most of those obtained seem to have come from a single cavity, the crystals standing free, and projecting to some length. Again they are found completely imbedded, as, for in

Eosphorite.

Childrenite, Hebron, Me. Childrenite, Tavistock. stance, in dickinsonite. These crystals are in general small; but occasionally imperfect crystals of a considerable size are met with, one of these exposes a width of about an inch, and is two inches long; in another, a single plane has a width of nearly two inches. The planes are seldom well polished, and only in rare cases are exact measurements obtainable. This is due in part to the fact that the surfaces of the crystals are often coated with drusy quartz, and again with minute crystals of apatite, and also because the prismatic planes almost always, and the pyramidal planes very commonly, are finely striated. This striation of the prismatic planes is a marked characteristic and gives rise to rounded barrel-shaped crystals analogous to those observed of tourmaline and many other species.