61. Brown Hematite.

This ore occurs in concretionary masses of a dark liver color, and compact structure, associated with nearly all the minerals of this mine-it very commonly forms a lining to cavities in galena, in which are found crystals of anglesite and cerusite; sometimes it lines cavities in the rock that are completely filled with cubical galena. Acicular concretions of the hematite are found traversing crystals of anglesite and cerusite. A specimen of the purest hematite gave for its composition

The remarkable feature of the fluor spar of this mine is the absence of color; all the specimens yet found being colorless and transparent. The crystals are very perfect and beautiful, yet small; it is sometimes in globular concretions, of crystalline structure radiating from the centre. The cube, which is the more common crystalline form, is sometimes very much modified by the truncation of the edges and angles. A specimen that was examined gave a sp. grav. of 3.15, and the following composition: Fluorine, Calcium,

Phosphate of lime,

48.29

50.81 a trace 99.10

It is associated with calc spar, and in some instances in a remarkable manner, mentioned under the head of calc spar. Galena and blende are interspersed through it. Its occurrence in the mine was first noticed at the depth of three hundred feet, and since then it has been found abundantly.

63. Calc Spar.

There are a variety of interesting forms and associations of this mineral. The two most common are the dog-tooth spar and the hexagonal prism with a three-sided summit, and occasionally the hexagonal prism with flattened summits like arragonite. Sometimes slabs of this mineral are found, with a surface of eight or ten square feet completely covered with prismatic crystals an inch or two in length, and from an inch to an inch in thickness; they are mostly vertical, but occasionally horizontal with double terminations. These crystals are sometimes of a remarkable character, being eight or ten inches in length and only a quarter of an inch in diameter, preserving a tolerably perfect hexagonal shape throughout the entire length; again, these slender forms are built up of small hexagonal prisms, their faces projecting

from the side. It sometimes happens that these slender crystals are crossed by one of the same diameter, and less length, firmly attached in the manner of a cross.

But of all remarkable crystallizations is one, where the small prisms are so arranged as to form a perfect double spiral arranged around an axis, (fig. 3); the specimen is three inches in length

2.

and ths of an inch in diameter, with the space of a 4th of an inch between each turn of the spiral. The spiral arises from one small prism crossing another at middle at a small angle of divergence (40°-50°), and so on in succession. These slender crystals are sometimes curved in a very remarkable manner.

Another thing to be remarked in connection with the calcite of this mine, is its singular associations; thus, we find groups of hexagonal prisms where a small cubical crystal of fluor, about the th of an inch, is inserted in a small pit in the summit of almost every crystal (fig. 4) without the occurrence of fluor spar on any other parts of the crystal. These crystals

appear to have been formed by successive
crystallizations. Dog-tooth spar seems to have
been first formed with these small crystals of
fluor spar on their extremities, and then by a
subsequent process, the calcite has closed
around the dog-tooth spar in the form of a
hexagonal prism with a three-sided summit.
The summit never closes entirely at the centre,
the fluor spar remaining visible on one side,
and where there is no crystal of fluor spar the
extremity of the dog-tooth spar is frequently seen.

Other groups of calcite crystals, have minute crystals of iron pyrites in the three faces of the summit, arranged near and per

fectly parallel to the alternate edges as seen in figure 5. 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 is found in three lines on the summit of every crystal running from the apex towards the edges, exactly bisecting each face as seen in figure 6.

In this instance, as well as in the former, the pyrites is 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.

64. Sulphur.

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, oxyd of manganese, iron pyrites, sulphate of baryta, indigo copper, black oxyd 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 120 feet, the phosphate and carbonate still continued with the galena, with fine large crystals of anglesite and considerable wulfenite; at 180 feet, phosphate very much diminished, carbonate and sulphate in fine crystals; arsenate was found here; at 240 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.

ART. XXV.-On the Meteorology of Oroomiah; by Rev. D. T. STODDARD.*

THE village of Seir, where we reside, is in the province of Oroomiah, in Northern Persia, in latitude 37° 28′ 18′′ north, and in approximate longitude 45° east from Greenwich. We are about 40 miles from the boundary of Turkey and 150 from that of Russia. The village is on the grassy slope of a mountain, which rises 2834 feet above the neighboring city of Oroomiah and 7334 above the ocean. The side of the mountain on which we live faces the northeast, and is consequently somewhat bleak in winter. The snow also lies upon it in the spring long after it has disappeared from the southwestern side.

From the village of Seir we look down on the very beautiful and extensive plain of Oroomiah, forty miles in length and from twelve to twenty miles in breadth, which possesses a deep alluvial soil and bears on its fertile bosom several hundred villages. The city of Oroomiah, the ancient Thebarma, situated near the centre of the plain, as well as many of the villages, is surrounded by innumerable gardens and orchards, and rows of poplars, willows and sycamores, which make large portions of the plain resemble a continued forest. The mountains of Koordistan encircle the plain on three sides, while to the east lies the lake of Oroomiah, studded with islands and reflecting the pure azure of an Italian sky.

This plain is watered by three rivers of moderate size, which come down from the Koordish mountains, and are distributed by a network of small canals and water courses over its whole surface. Without artificial irrigation but few crops can be brought to maturity, although here and there wheat fields are cultivated on the slopes of the neighboring mountains, which are wholly dependent on the rains of the spring and early summer, and sometimes yield a tolerable harvest.

The principal productions of the plain of Oroomiah, the annual mean temperature of which is of course considerably above that of Seir, are wheat, barley, corn, millet, flax, tobacco, rice, cotton, castor oil, apples, pears, plums, grapes, (which are cultivated in immense vineyards) cherries, apricots, nectarines, peaches, melons, pomegranates, almonds and the jujube. The fig, with care, may also be cultivated, but is often destroyed by the cold of winter.

The lake of Oroomiah, the ancient Spautes, is about ninety miles long by thirty broadt. Its water has been thus analyzed by President Hitchcock:

* From a letter to Professor D. Olmsted, dated Seir, Oroomiah, January, 8, 1855. Its elevation above the ocean is 4100 feet.

In the water of this lake it is impossible for a man to sink, the specific gravity being 1.155, and those who bathe in it come out encrusted with salt. In the summer, its shores are also fringed with a broad, white margin of salt, produced by evaporation. The lake exerts of course a marked influence on the climate of this region, and, as will be seen from the tables, produces a regular land and sea breeze in the summer months. During the day a light wind blows from the lake, aad during the night a fresher wind from the lofty mountains of Koordistan, which rise some forty miles west of the lake, to the height of 10 or 12 or perhaps 13 thousand feet above the ocean, and generally retain on their summits, even in summer, deep masses of snow. The amount of watery vapor is thus probably much greater in Oroomiah than in many parts of Persia, which present almost the barrenness of the Arabian deserts.

It should be mentioned in this connection that all the mountains in Northern Persia are destitute of trees, and many of them rise to a great height in naked rocky summits. Indeed, in the valleys and on the plains, it is rare to find any trees, except those planted by the hand of man, and a stranger, as he looks down on the luxuriant plain of Oroomiah, can hardly be made to believe that the millions of trees before him are entirely an artificial growth.

I regret that it has not been convenient for me to take hourly observations on the temperature, at least so far as to fix the proper times of observation for this region. Hourly observations, which have been made in countries remote from Persia and in climates entirely different from this, on the basis of which the tables of Kaemtz and others are founded, I have supposed would avail little for my purpose. The hours selected were those which suited best my convenience. I also desired to procure the extremes of temperature, which are here almost uniformly just before sunrise and at two or three in the afternoon. Of course, the average of the tables is below the actual mean temperature, though I am unable to say how much. It may however be interesting to mention, that a very large spring, just above our house on the mountain side, maintains throughout the year the temperature of 53° Fahrenheit. I have never found, summer or winter, a variation of more than half a degree.

*See an article in the Transactions of the Association of American Geologists and Naturalists.