« PreviousContinue »
perfectly parallel to the alternate edges, as seen in figure 4. Every crystal in the group is thus furnished with a set of crystals of pyrites.
In another group of crystals the pyrites, in equally small crystals, are found in three lines on the summit of every crystal
running from the apex toward the edges, exactly bisecting each face, as seen in figure 5.
In this instance, as well as in the former, the pyrites are inserted entirely beneath the surface of the crystal, which is perfectly smooth.
The calcite is found in large crystals in dolomite, and is associated with most of the ores of the mine. It sometimes gives rise to pseudomorphs of molybdate of lead and carbonate of lead. These pseudomorphs are mere shells, however, retaining the form of the calcite.
Sulphur occurs in the form of small pale greenish-yellow crystals. They are transparent and disseminated through cellular galena, which appears to have undergone partial decomposition. The galena in which it occurs is frequently associated with copper and iron pyrites, and in some rare instances with carbonate and phosphate of lead.
The other minerals occurring in the Wheatley Mine are finely crystallized quartz, oxide of manganese, iron pyrites, sulphate of baryta, indigo copper, black oxide of copper, and dolomite.
Of the other mineral veins in this region none have yielded the beautiful mineral species furnished by the Wheatley vein. The Perkiomen vein, five miles from the Wheatley vein, has furnished fine capillary copper, indigo copper, fine acicular crystals of sulphate of baryta, crystallized copper, and some crystals
of sulphate, carbonate, and yellow molybdate of lead; but these last were small, and bear no comparison to those described,
It was hoped that something might be learned concerning the formation of the minerals of this vein; but the difficulties and uncertainty attendant upon the study of questions of this kind make it prudent to postpone any views that might be suggested. It may, however, be well to remark that in opening the vein, and descending from the surface for the first thirty feet, the phosphate of lead was very abundant, with some galena and carbonate. A little lower down the phosphate was less and the carbonate more abundant. Wulfenite and anglesite began to appear at one hundred and twenty feet. The phosphate and carbonate still continued with the galena, with fine large crystals of anglesite and considerable wulfenite. At one hundred and eighty feet phosphate very much diminished; carbonate and sulphate in fine crystals. Arsenate was found here. At two hundred and forty feet blende, calamine, and fluor-spar appear with considerable dolomite and but little phosphate of lead, galena forming almost the whole lead-ore. Anglesite is found, but in smaller crystals. These observations may hereafter lead to some conclusions as to the manner of the formation of these minerals, but at present I prefer dismissing the subject without further remarks.
TWO NEW MINERALS.
MEDJIDITE (SULPHATE OF URANIUM AND LIME)-LIEBIGITE (CARBONATE OF URANIUM AND LIME).
The minerals here alluded to were found associated with a specimen of pitchblende from the neighborhood of Adrianople, Turkey; it was quite impure, and a portion of it contained. crystals of copper pyrites. On the surface of the pitchblende, besides the two minerals in question, there existed crystals of sulphate of lime and a little oxide of iron.
MEDJIDITE (SULPHATE OF URANIUM AND LIME).
This mineral is of a dark-amber color, transparent, of imperfect crystalline structure, fracture vitreous, although the surfaces exposed are sometimes of a dull-yellow color, arising from the loss of water. It is found on the surface of the pitchblende associated in some places with crystals of sulphate of lime. Hardness about 2.5; specific gravity not known.
Chemical Characters.-Heated gently it loses its water, becoming of a lemon-yellow color. Heated to redness it blackens (being converted into oxide of uranium and sulphate of lime). It is insoluble in water, but dissolves readily in the smallest quantity of dilute hydrochloric acid; (in this way, had it been necessary, I might have separated it from any adhering sulphate of lime.) The acid solution gives a tolerably abundant precipitate with hydrochlorate of baryta, and a red-brown precipitate with ferrocyanuret of potassium; bicarbonate of ammonia forms a precipitate that is redissolved by an excess of the ammoniacal salt; oxalate of ammonia added to this solution demonstrates the presence of lime. Farther examination detected no other substance.
So far as the small quantity at my disposal enabled me to make out its composition, it would appear to be a salt similar
to the following one (liebigite) with less water, and sulphuric instead of carbonic acid, the acid being derived from the decomposition of the pyrites associated with the pitchblende. Its composition is represented by ÜÏ+Ča Ö÷15Ĥ.
This mineral is called medjidite in honor of the reigning Sultan of Turkey, Abdul-Medjid, who exhibits a most decided patronage of both the arts and sciences, certainly much more than any of his predecessors.
LIEBIGITE (CARBONATE OF URANIUM AND LIME).
This mineral is not found crystallized, but occurs in the form of a mammillary concretion, having an apparent cleavage in one direction. It is of a beautiful apple-green color, transparent, with a vitreous fracture. Hardness between 2 and 2.5; specific gravity not ascertained.
Chemical Characters.-The mineral admits of ready separation from the pitchblende, and owing to its color and transparency is easily freed from the smallest portion of foreign matter. Heated gently, it loses water, acquiring a yellowishgray color; heated to redness, it blackens without fusing, and on cooling returns to an orange-red color; heated strongly before the blowpipe, with or without charcoal, it blackens, and on cooling remains so; with borax it gives a yellow glass in the oxidizing and a green glass in the inner flame. Its property of blackening when heated to redness, and assuming an orange-red color on cooling, made me suppose that it might contain vanadic acid; but, as will be seen a little farther on, its reactions proved this not to be the case. As yet I believe that this property is not known to belong to any other natural combination of uranium.
The mineral dissolves readily in dilute acids and with violent effervescence, affording a yellow solution that gives a yellow precipitate with ammonia and its carbonate; but the latter in excess redissolves most of the precipitate, and what remains is found to be carbonate of lime. The carbonate of ammonia solution when boiled redeposits a yellow precipitate. In a neutral solution sulphureted hydrogen produces no precipitate, but the hydrosulphate of ammonia furnishes one of a brown color, and the ferro-cyanuret of potassium one that is reddishbrown.
The above properties show the presence of water, carbonic acid, lime, and uranium; farther examination gave no evidence of the presence of any other substance.
The amount of this mineral in a state of purity was too small to allow me to make as minute a quantitative analysis as I should desire; but, owing to the simplicity of its composition, the true nature has been very nearly if not exactly made out. The water was estimated by heating it to 400° Fah.; the carbonic acid by what was lost in dissolving it in hydrochloric acid in a small apparatus properly arranged; to the acid solution bicarbonate of ammonia was added, which redissolved all the precipitate first found; oxalate of ammonia when added to this precipitated the lime (which was afterward estimated as a sulphate); the solution filtered from this precipitate was boiled and the uranium deposited itself as a double salt that was heated to redness, and the oxide estimated in the form of olive-colored oxide. (Peligot's atomic weight for uranium was the one employed, 750; oxygen 100.)
The mean of two analyses, one of 85 and the other of 65 milligrammes, is
The composition of the mineral is represented by Uc+Ca Ö +20 H. The pitchblende upon which the liebigite is found was analyzed, and at some future time I may have occasion to allude to this analysis with some remarks upon the salts of uranium; for the present suffice it to state that the pitchblende contains lime associated with the oxide of uranium, a circumstance that, along with the tendency of oxide of uranium to form double salts, accounts for the formation of both the liebigite and medjidite.
I have thought proper to give this double carbonate the name of the distinguished chemist of Giessen, as a demonstration of the high value I set upon his memoirs and important contributions to the science of chemistry in general.
Liebigite I have also found in one of the European localities of pitchblende — namely, Johanngorgenstadt. The first