are of little value compared to the actual reduction of large quantities of the ores in working processes.

Other lodes of this district.-My notes contain mention of over fifty lodes or veins, most of them probably distinct, which I visited in the course of my explorations of the San Francisco district, and which belong to the east-and-west system. The parallelism between the lodes of this system is almost exact, and there is a great similarity in their mineralogical character.

The 'Skinner,' on the south side of Silver Creek, is one of the most conspicuous, forming like the Moss lode bold and fantastic crests, rising sometimes in slender needles to a remarkable height. The boldest outcrop is called the "center claim," of 1600 feet. But those portions called the Rochester (1800 feet). and the San Francisco (2400 feet) are nearly as bold. This lode shows drusy quartz, both compact and cellular and ferruginous with numerous cavities where fluor-spar has been weathered out. Hornstone is also seen frequently. Very small traces of sulphids show at surface, which is much stained by black oxyd of manganese, rendering portions of the outcrop quite black.

This vein varies from 50 to 150 feet in thickness. Its walls of ash-colored feldspathic porphyry are seen in places beautifully polished on the line of the dip 70° N. It appears glued first to the porphyry, without a lining of clay, (fluccan), but this is so commonly the case in the outcrops of Nevada that it is no proof of the absence of this important character of a true vein at a moderate depth.

An exploratory shaft has been sunk near the center of this claim on the foot wall, at a point designed to cut the lode at the depth of 100 feet, but at a depth of 50 feet the resources of the explorer gave out. Eighteen feet of water in this shaft confined my observations to the materials thrown out, showing the correctness of a statement made to me, that a branch vein or offshoot of the main vein had been cut, carrying green and purple fluor in octahedrons in a quartzose and feldspathic gangue, with occasional gray spots of minutely diffused sulphid of silver. Three assays of the ore from this shaft proved the presence of silver to the value respectively of $25, $74, and $83 to the ton of 2000 lbs. From a second shaft sunk on the N.E. side of the wash, in the body of the vein, to a depth of 25 or 30 feet, I obtained beautiful octahedral crystals of green, white, and purple fluor spar. The gangue and the whole mineralogical character of this vein, so far as explored, is of the most promising character, and it offers a most legitimate field for judicious exploration, with a reasonable expectation of the discovery of silver ores in remunerative quantity. At the same time it must be remembered that such an exploration is sure to be costly and its result is always doubtful.

The Parsons, Hurst and Leeland are other gigantic lodes,

south of the Skinner and of generally similar character, but, at the time I saw them, almost completely unexplored.

Some of the smaller lodes of this district appear to me to offer the hope of a much less costly exploration, and with the promise of quicker returns. Of this class I may mention the Caledonia and Dayton, a few hundred feet south of the Moss lode, and the Quackenbush and Knickerbocker, some distance south of the Skinner and Parsons. These veins are from three to ten feet in thickness, well defined, and showing at surface all the characters of true metalliferous veins. Besides well characterized and abundant iron gossan in cellular quartz, I observed in them fluor spar, feldspar, green carbonate of copper, horn silver, and free gold. Samples from these outcrops, collected by myself, yielded when worked in an experimental mill, from forty dol lars to two hundred and fifty dollars per ton of two thousand pounds.

In no other mineral district which I have seen are there so many remarkable outcroppings of quartz veins carrying the precious metals, crowded into so small an area and on a scale of such magnitude in development as in the San Francisco District.

In the vicinity of Austin, (Reese River) Nevada, the veins are more numerous, probably, but are also much smaller and quite inconspicuous, having, in fact, almost uniformly no outcrops to attract the attention of the explorer.

Both districts are situated in a desert and inhospitable region, but the fervid heats of the Arizona summer are fully counterbalanced by the severe cold and snows of the more northern locality. Supplies can be brought with tolerable certainty by sea and river to Hardy's Landing, immediately in front of the San Francisco District, and within five miles of the Moss lode.

With these facilities for development we ought not to remain long in ignorance of the true character in depth of these very remarkable mineral veins, nor is it too much to hope that they will, with an honest and prudent use of capital reward the adventurers with handsome returns for the capital employed in the exploration.

Of neighboring mineral districts.—My observations extended east of the San Francisco District to Trout Creek, a branch of Bill Williams' Fork of the Rio Colorado, where there is a min⚫eral district called the Wauba Yuma, about 60 miles east of the Colorado, and in a region entirely beyond the present limits of civilization. Passing the range of Boundary Peak, over a crest of volcanic tufas and red porphyry rocks of some 1500 feet elevation at the point of crossing, above Allen's Camp, or over 3000 feet above the river,' the traveller descends eastwardly in

The peaks on either side of the pass are, however, much higher, but I had no opportunity to measure them by the barometer.

AM. JOUR. SCI.-SECOND SERIES, VOL. XLI, No. 123.-MAY, 1866.

a dry valley, called Massacre Valley, from the sad tragedy of the murder of a large party of Texan and Arkansas emigrants in 1857 by the Mojave, Wallupi and Pah Utah Indians. We found the melancholy evidence of this catastrophe scattered along the line of Beale's Road for several miles, over seventy persons with their teams and baggage wagons having been destroyed. The bleaching bones of the oxen, half burned remnants of waggons, with cooking utensils and household furniture scattered about or lying as they fell, attest the savage ferocity of these treacherous tribes. About twenty miles beyond the easterly margin of the San Francisco District, there is an entire change in the geological character of the country. The porphyritic and volcanic rocks give place to metamorphic schists, gneiss, and granitic rocks abounding, with numerous veins of white quartz. From the Rio Colorado to the eastern limit of the Massacre Valley, 30 miles or more, the rocks are entirely porphyritic or volcanic. The same rocks which are seen on the west side of the Colorado are repeated here. The mountains possess a fantastic, almost grotesque outline, due, probably to their peculiar mode of decomposition. Many needle-shaped porphyritic masses adorn the ridge and are thrust through horizontal and gently inclined beds of volcanic tufa and cement of various striking colors, usually light, sometimes almost white, variegated by zones of brown, red, chocolate, and yellow. Large blocks and irregular fragments of volcanic or basaltic rocks, usually black or deep brown, are seen implanted in the overhanging and undercut cliffs of tufa and cement 250 to 300 feet high along the narrow gorge through which the trail crosses the crest, near "Meadow Springs." These volcanic beds appear to be of sub-aqueous origin. All the loose river drift and boulders on the plane are cemented into a firm concrete with a white cement derived probably from these beds.

The change in the geology of the region is very marked in the transition from volcanic rocks to those of the granitic family, and is accompanied by a corresponding change in the character and direction of the mineral veins, and the commencement of a region better wooded and watered than that previously described. Near the western margin of the Wauba Yuma District occurs a considerable vein of auriferous quartz, accompanied by ores of copper and sulphurets of iron. It first appears in a pretty high granitic mountain to the northwest, and its course has been traced about three miles to the southeast. This lode, which has been called the "Pride of the Pines," appears to be about ten feet wide, and possesses promising characteristics. The sample collected by me, although showing no free gold, yielded $30 to $50 to the ton of assay. It possesses the characteristics common to the auriferous lodes of the Sierra Nevada, and the same general N.W. and S.E. direction, while, it will be remembered,

the silver veins of the San Francisco District are nearly east and west in direction.

The granitic range in which the "Pride of the Pines" vein occurs extends for at least fifty miles, in a line nearly north and south, and forms a mountain mass of no mean proportions. Its altitude I could only conjecture, having sent my barometer in another direction, and crossing the ridge only at subordinate points. Its crests, however, may be from five to six thousand feet above tide.

Immense drift deposits of angular fragments without arrangement occur upon the flanks of this range, and so greatly resembling in their character glacial moraines as to command my careful notice. In a dry arroya which had been cut by torrents through this ancient drift, I saw for two and a half miles a section, averaging perhaps one hundred feet in depth, of the mass of one of these moles of glacier-like materials, chiefly angular fragments of granite, some of quite large dimensions, mixed with smaller angular fragments, sand and mud, with no trace of arrangement or stratification whatever. These moraines (if they are such) are of all dimensions, from one mile to eight miles in length, some of them as regular as a rail-road embankment and forcibly recalling those of unquestionably glacial origin jutting out upon the American Desert from the eastern escarpments of the Sierra Nevada near Mono lake, Aurora, and between Wellington's and the Palmyra districts.

These Arizona mounds run southeast from the main mountain mass, in lines seemingly parallel but really radii of the mountain valleys or gorges, between which they occur, falling away in gently inclined planes from the ridge. On their outer edges. some traces of stratification appear, as in river drift, but this appearance seemed plainly a partial rearrangement of the materials by the torrents to the course of which they are limited. I record the observation with the impressions made at the time. My field notes contain the remark "true glacial drift." The latitude was about 35°, lower than true glacial phenomena have been recognized, if I am correctly informed. There were no exposed surfaces of rocks to show glacial scratches, and the exigencies of travel in this difficult region did not permit me to ascend the rocky peaks in search of them.

These alluviums, whatever their origin may be, cover an area ten miles to fifteen miles in width, going east of Pine Mountain ridge to the next and parallel ridge, which I have in my notes called "Castle Ridge." The recurrence of volcanic rocks and wide spread sheets of basaltic lava, as a capping to the mountains and hills, gives it a character entirely in contrast with the familiar features of the metamorphic and granitic mountains just noticed. These features are especially seen in a lofty table mountain of the 'Castle Ridge' on the traveller's left, as he leaves

Pine Mountain ridge behind him. This bold land-mark I named in my notes "Mount Brewer." "Fortress Rock," on Trout Creek, is another fine example of the same kind, but the valley north is filled with similar table mountains from a few hundred to a thousand or twelve hundred feet above the surrounding country. Here the same horizontal and gently inclined beds of light colored tufas already noticed as occurring near Silver Creek, fifty miles or more west of this, recur and are capped in a like manner by basaltic columns.

Enormous dikes or reefs of quartz and of coarse quartzose feldspathic granite cut through the reddish gneissoid granite which forms the basement rock over a large part of the Wauba Yuma District, rising in one case 100 to 150 feet above the cañon which cuts the vein at a point where I examined it, and where it is 50 feet thick. I could not discover in those gigantic veins much evidence of any metallic value, nor had there been any exploration upon them.

The Sacramento District, about 45 miles N.E. of Fort Mojave, I did not visit, but inspected a large collection of argentiferous galena from its veins, made chiefly by soldiers of the Post. These lead veins occur in metamorphic rocks, and are such in size and metallic value, so far as I could learn, as to lead to the belief that they will one day be worked when labor and supplies are cheaper and more abundant, and they may furnish a most important auxiliary to the treatment of the silver ores of adjacent districts.

The Irataba district, south of Fort Mojave, comprises a number of veins carrying copper, but few of them, in the opinion of my assistant, Mr. Frank Sample, who visited them, are worthy of exploration.

ART. XXXVII-A method of Giving and of Measuring the angles of Crystals, for the determination of species, by the use of the Reflecting Goniometer; by JOHN M. BLAKE.

It seems desirable that more general use should be made of angular measurements of crystals for the purpose of determining species, than the ordinary methods of measurement and comparison will allow.

The time and study required to understand the various forms of symbols adopted by different authors, and then to locate the planes on the given crystal before making the measurements, make the pursuit of the subject in this way a difficult matter, even to those who have spent considerable time in the study.

Now it is possible to describe a crystal, giving measurements which will locate every plane occurring upon it, without the use