Prof. HALDEMAN illustrated the above paper by examples from Indian and other languages containing the various glottals, clacks, and whispered syllables, to the great amusement of the audience. Adjourned.

W. I. BURNETT, Secretary.

Seventh Day, August 21, 1849.

AFTERNOON GENERAL SESSION.

ON RUTILATED QUARTZ CRYSTALS FROM VERMONT, AND PHENOMENA CONNECTED WITH THEM. BY FRANCIS ALGER.

Mr. ALGER presented a paper on the quartz crystals from Waterbury, Vermont, containing acicular or capillary Rutile, and exhibited illustrative specimens of great perfection and beauty. He compared them with other specimens from the Alps and Brazil, and pointed out some important phenomena in which they differed from those, and all other rock crystals he had ever seen.

Erratic masses of rutilated quartz had, from time to time, been found in Waterbury, and several of the neighboring towns, and they had even been picked up in New Hampshire; but their geological association, or the character of the rock from which they originated, had not been well understood until recently. Mr. Alger had lately visited a remarkable locality of this mineral, where a true vein, two feet or more in width, had been brought to light in making a deep cut through a hill in Waterbury, on the line of the Vermont Central Railroad. The rock is a very tenacious talcose slate, sometimes passing into mica slate, and prevails to a great extent in this part of Vermont. Metaliferous minerals are rarely contained in it, but veins of quartz are common. The vein here referred to, consisted principally of common amorphous quartz, presenting internal cavities or druses, lined or studded with projecting prismatic crystals, sometimes colorless and transparent, but more frequently of a smoky color, or brownish yellow tint, (Caringorm.) The pure glassy white crystals, are but rarely penetrated by the acicular rutile, while the colored varieties abound with it, and seem in fact to owe the intensity of their color to the very prevalence of it through their substance.

The rutile is sometimes grouped in tufts of radiating crystals, proceeding from a common point, and shooting through the quartz; this being also the ordinary manner of its occurrence in the Brazilian specimens. The direction of many of these diffused crystals in the position they now occupy, would seem to show that they had been

subjected to some electrical or polarizing influence, by which they had been arranged very nearly in a line parallel with that of the apex or perpendicular axis of the crystals of quartz in which they are imbedded. It would seem that they were once floating, as it were, in the transparent and liquid medium of the silicious mass; or else, what is more probable, in the simultaneous crystallization of both quartz and rutile, slowly or otherwise, there was superadded a polarizing influence which caused them to converge towards one point. Or again, it may be that these peculiarities are confined to those quartz crystals which projected downwards in the cavity of the vein at the time of their formation; and thus the rutile, from its greater specific gravity, would have a tendency to crystallize and extend itself downwards, rather than in any other direction. Mr. Alger could not state from actual observation at the locality, whether such was the fact. The appearance referred to is the most marked in those crystals in which the rutile exists in the most delicate hairlike and needle-shaped forms, (Venus hairstone ;) and, in some instances, these delicate prisms are bent towards the ends most remote from the apex of the quartz crystal. They are sometimes four inches in length.* By transmitted light, their color is reddish brown; lustre like that of polished copper. Some few of the needles are entirely black, and closely resemble schorl. It was the opinion of Mr. Kennedy, a scientific engineer, and a very close observer, who was present at the opening of the vein, that the crystals of quartz enclosing rutile, were confined to one side only of the vein, thus indicating two periods in its formation, in one of which no rutile was present to intercrystallize with the mass. All the recently obtained crystals are very much discolored by iron rust, and the vein appears to be “ run out." But its loss will undoubtedly be soon supplied by other sources.

Prof. Hubbard, of Dartmouth College, in whose possession is the finest specimen of this mineral found in the United States, first noticed a most interesting fact in regard to these crystals, namely, that the needles of rutile in some cases, had shot completely through the quartz crystals, and stood out in relief upon their surfaces, as if protruded by the sudden effort of their crystallization. The same appearances were presented by one of Mr. Alger's specimens, to a small extent. If produced in the manner supposed, the quartz must have been in a liquid state; if not produced in that manner, the crystallization of

*The polished specimens in which these prisms are exhibited, (known in French jewelry as Flèches d'amour) are rarely surpassed in beauty by the finest to be met with in foreign collections. The reticulated forms are thus shown in great perfection.

the rutile must have continued after that of the quartz had ceased. The latter seems the most reasonable supposition, and is favored by analogous phenomena in other crystallized minerals.

IMITATIVE FORMS OF MICA CONTAINED IN THE QUARTZ.

The surfaces of two of the large crystals exhibited by Mr. Alger, as well as several smaller fragments of crystals, were covered by minute but very brilliant scales of gold-colored mica; and these sometimes penetrated the quartz in company with the rutile, and, in the same manner, seemed confined mostly to the darkest colored varieties of the quartz. But the forms assumed by this mica, are curious and altogether unique, for in the substance of the crystals, it has assumed the most fantastical forms, appearing in tortuous and vermicular ramifications, some of them bearing such a striking resemblance to organized bodies, as to give the first impression that they are actually the remains of insects or worms. The figures on the next page present a correct representation in a magnified form, of some of the most curious of these appearances exhibited by Mr. Alger's specimens. He had dissected out several of them, and found them to be composed entirely of small plates of mica more or less closely united parallel with the basal cleavage of the mineral. In fact, they are elongated hexhahedral crystals of mica, twisted or distorted into every imaginable shape. Their laminated micaceous structure is shown perfectly by the microscope, and is represented in the figures. The resemblance of the third figure on the fourth row, to some species of Araneides, is not too remote to suggest them to the mind instantly; and the general resemblance of several of the figures to the common blood leech, (Sanguisuga medicinalis,) is still more striking. But the origin of these resemblances was evidently fortuitous, and could not have been in any way connected with organic matter. They are interesting principally as furnishing a new fact in the department of imitative mineralogy, and they appropriately suggest the term vermiform mica as most characteristic of their general appearance.

The straight lines seen passing through several of these figures, are intended to show the needles of rutile that actually intersect these concretions of mica in the body of the stone. In some of them the rutile passes through the circular space left by the folding over of the mica, and its crystallization does not seem to be interrupted by the mica in any case. A characteristic feature of rutile, but never shown in any of the specimens from this locality, (i. e. the geniculated forms,) seems to be somewhat assumed by the mica, and

is best shown by the second figure in the lower row.* The color of this mica by transmitted light, is a pale green, and the mineral seems to agree in external characters with the substance from other localities. Considerable quantity of it was found loose in the vein, mixed with broken crystals of rutile. The only appearances at all analogous to those just described, which had come to the knowledge of Mr. Alger, were those mentioned and figured by Dr. McCulloch, and described in Vol. II. of the Geological Transactions of London. But in this case, the substance was chalcedony, and the imbedded masses composed of chlorite, had nothing of a crystalline structure, and in fact were rather imitative of vegetable, arborescent forms.

STRIATED QUARTZ CRYSTALS.

THE above figure represents some of the stria which appear on the acuminating planes of the crystals, and are parallel with their edges of combination with the adjoining planes, as shown in the figure on the next page. They are usually mere superficial triangular lines so slightly impressed as to be visible only when held in a particular position in regard to the light; but in a few cases, these configurations, commencing at a small point before the crystal had attained its full size, continue to widen with every fresh layer of particles deposited upon the faces of the crystal, until they produce cavities of considerable depth. That they were formed in this manner, is indicated by the step-like appearance of the sides of these cavities an appearance which is more strikingly presented in a few cavities of a different * Prof. Hubbard's specimen presented the appearance in so marked a manner, as to lead to the impression they were rutile.

† A portion of this carefully separated, was found to lose nearly 15 per cent. of water when heated to the melting point of glass. A peculiar empyreumatic odor was at the same time given out, but there was no reaction of fluorine. Exposed in a platinum crucible to a white heat for twenty minutes, it became grayish black and partially fused into a mass. In this state it was slightly magnetic. The large proportion of water seems to ally it with ripidolite, or perhaps with hydro-inica from the Alps-Wasserglimmer of M. Morin. It will be further investigated.