due to men and to their industry. The ascent from the eastern side to Tananarive is startling from this point of view. The canal from Pangalanes permits crossing the coastal zone, marshy and warm. The arduous ascent of more than 1,500 meters of jagged rocks, whence fall raging cascades in the midst of the humid luxuriance of a tropical forest, leads to vast plateaus covered by the grassy steppe which is prolonged, barren, and dry until the moment when the high hills of Tananarive commence to carve themselves against the sky, coming nearer little by little, then appearing in the midst of verdant rice plantations with all the details of their red beauty.

The means of transportation which permitted me to reach my destination were not less varied. The slowness and the lack of comfortable navigation through the canal on the plain made us better appreciate the speed and elegance of the railroad—a bold undertaking, which in less than 13 hours climbed over the high rounds of the titanic trestle, leading to the neighborhood of Ocean by the side of the battered plateau on which, much farther still, the Malagasy capital stands. It was by automobile that the 172 kilometers which separate Tananarive from Antsirabe, my first center of exploration, were traversed and I descended from a vehicle of the latest model only to mount a "filanzane" (seat suspended between long poles).

At the risk of being called an old retrograde academician, I distinctly state that between the automobile and the filanzane my sympathy for the geologist goes straight to the latter.

The journey from the capital to Antsirabe was like the cup of Tantalus for me. Over this road, still new, we rolled along with dizzy speed; before my eyes, accustomed by a month of the bush to the monotony of the red earth which covers the greatest part of the island, the rocky walls recently torn up by dynamite appeared like flashes of lightning exposing to the sun their marvelous freshness. Upon the slope some broad surfaces of granite, reflecting white or rose, were loosened, magnificent, with innumerable dark spots, basic inclusions, which I seek throughout the world that I may learn from them the secret of the genesis of the rocks which inclose them; then, as in a giant kaleidoscope, there succeeded some gneiss in many colored strata, revealing the complexity of their nature, some veins of every variety. What more do I know?

Each turn of the wheel brings a new temptation. My hammer burns my hands. But alas! deaf to my prayers, the conductor of the infernal machine, bending over the steering wheel, slave to the hour, refuses the slightest stop and we keep rolling on.

With the filanzane these distractions are unknown. Nicely perched on a little seat of cloth between two long bars resting on the

1 The railroad attains the height of 1,520 meters between the stations of Ambatolaona and Manjakan driana.

shoulders of four strong fellows, the traveler is master of his destiny. The measured step of the porters, the resulting rhythmic movement, hardly disturbed each minute by the interchange of the bushmen, are not without charm and induce revery.

In the plain, on a track well marked, the Malagasy loves to take a sinuous course, but just as soon as the land changes, he uses nothing but the straight path. It happens sometimes that one is almost erect in the stirrups during steep descents, or the head is lower than the feet on steep ascents. The inexperienced sufferer makes sad reflections on certain proprieties, new to him, of the shortest way from one point to another, but he soon reassures himself as he learns the skill, the wonderful steadiness of his servants, and without fear trusts to them, and feels himself carried at a bound over all obstacles.

This mode of transportation is not slow, for it is possible to make 70 kilometers in a day, though about 50 kilometers is a good average, and can be maintained for several weeks with the same men on condition that some village be reached from time to time, when the bushman may find fresh meat, a good night's lodging, and rest.

The Malagasy porter is a big child, laughing, talkative, obliging, temperate, easily contented, and from whom one can gain a great deal, when he is treated in an equitable, kindly way, but with firmness.

At the end of my four months of uninterrupted round in the bush, I was alarmed about them only once. One morning, their humorous stories, related as usual at the time of departure, were longer than was customary. The stories were told in an animated dialogue between two of the band, who replied to each other in a tone growing sharper and sharper, and they became more and more excited by the applause for some story well told, until the two chief actors caught each other by the hair on some trifling pretext. I had to intervene to prevent a general fight. My cook, who was interpreter, having stayed behind, forced me to await his arrival to learn the real cause of the conflict. The debate was in a way philosophical. The question was whether it is best to be economical each evening with one's wages or if it be not better to spend them as most of these talkers had very certainly done the night before.

It was in that equipage that I thoroughly explored the region of precious stones, which forms a great rectangle about 200 kilometers long from north to south and 60 or more wide from east to west.1

1 The principal centers are to the northwest of Antsirabé, the outskirts of Miandrarivo (Ampangabé in particular); to the west of Antsirabe, the region situated to the west (Anjanaboana) and to the south of Betafo (Tongafeno, Antsongombato, Zamalaza, etc.); to the south of Antsirabe, the valley of the Sahatany and its vicinity; Sahanivotry, to the east of Mount Bity, then more to the south on the other side of the Manandona, a series of beds situated to the northwest and to the west of Ambositra and then still farther south, the region of Ikalamavony (see vol. 4 of the "Minéralogie de la France et ses colonies").

The valley of the Sahatany River southwest of Antsirabé, may be taken as an example. I came upon it in going over Mount Bity, a long jagged ridge more than 2,000 meters high, formed chiefly of white quartzites, sometimes rising vertically, sometimes bedded in great slabs which are crumbled into very fine sand or into large grains of quartz, translucid and sharp.

The Sahatany is only a small tranquil river, flowing into the tumultuous Manandona with many crocodiles, the only harmful animals of Madagascar. It irrigates a large valley in which there is a remarkable relation between the vegetation and the mineralogical nature of the soil. This is essentially formed by parallel bands of quartzites, mica-schists and marbles. A monotonous mantle of high grasses conceals the first two rocks, while the limestones, bright in their white nakedness, support numerous aloes (Aloe macroclada Baker) whose trunks, more than a yard in height, are surmounted by large bouquets of green leaves. These aloes with their queer shapes, sole arborescent vegetable of the valley, reveal at a distance the composition of its soil as easily as on a geological map.

The precious stones are all found in the pegmatite veins, intercalated between strata of metamorphosed sediments or traversing intrusions of granite. These pegmatites are very heterogeneous; their two essential elements, quartz and microcline feldspar, at times of a vivid green tint, and constituting the "stone of the amazone," are of great size. Among these rocks, it is interesting to distinguish two types, as well from the scientific point of view as because of their practical use. In one, the quartz often has the beautiful rose color that is sought after for making small ornaments. The mica, when it appears,' is that potash-mica, in great colorless sheets, the use of which for portable stoves has made the mineral popular.

Only one gem exists by itself, the beryl,' but its crystals are at times enormous;3 I brought back one which measures nearly a meter. You should not believe, however, that these colossal-like crystals are entirely transparent; the limpid portions are seen only here and there, in the midst of a fissured mass, cloudy or opaque. The colors that are most sought after, those of the aquamarine, are the various shades of blue and the sea green, but one sees also some colorless varieties and yellow or rose colors; the beautiful striking green color which characterizes the emerald is unfortunately not found there.

1 Mica is often lacking in the gem-bearing pegmatites. The muscovite is not worked there, though a very good quality of it is found in some special pegmatites, notably in the massif of Olotsingy, to the south of Betafo.

I have recently found a small quantity of uncolored topaz at Ampangabé, 1913.

These crystals of beryl are hexagonal prisms, very long on the vertical axis; they are very often types of weak density, of which I will speak further on.

The stones that are most highly esteemed are those of sky-blue shade (Ampangabé, etc.) or of a very special dark blue, with a black tint (Tongafeno, Fefena, etc.).

In several deposits situated outside the Sahantany1 region there is also found an abundance of monazite, a cerium phosphate sought for on account of the small quantity of thorium which it contains, thorium entering into the composition of gas mantles used for intensive lighting. One can find there also some uranium bearing titanotantaloniobates from which the precious radium is extracted.

It is not rash to think the day is not far distant when these minerals will no longer be mere scientific curiosities, but will become material profitably turned to account.

The second group of pegmatites is characterized by a greater variety of gems. The most abundant is tourmaline. This substance furnishes with beryl and corundum an illustration of the fact that the color of minerals does not generally constitute one of their essential characteristics. One can not conceive of malachite other than green, but very rare are the minerals which, like that, have a color which belongs to them alone. The coloration of nearly all species of minerals, and particularly some precious stones, is only a natural tint, existing ordinarily in such a small proportion that in many cases one may still dispute its nature.

In the Sahatany region the transparent tourmalines are the most beautiful gems, running all the possible gamut of colors. Rarely colorless, they are red and of many different reds; pigeon blood like the beautiful ruby, reds more or less tinged with violet, fading away to the most delicate rose; there are some greens and blues, some browns with now and then a smoky tint, some golden yellows, and one of dazzling gold. Here the colors are uniform in the same crystal, there they alternate to form harmonious blendings.*

By the side of these transparent stones are also found, as in the preceding pegmatites, a black tourmaline of no possible use." Though from a reminiscense of the war of conquest in which the Senegal sharpshooters played a rôle that the Malagasys have not forgotten, they call these stones "senegal."

1 The deposits where this mineral exists in great abundance and in large crystals are to the north of Betafo (Ampangabé, Ambatofotsikely, etc.); it is there accompanied by ampangabéite, columbite, strüverite, and some bismuth minerals. (A. Lacroix, Bull. Soc. franç. minér., vol. 34, p. 63, and vol. 35, 1912, p. 76.) "I have distinguished two groups among these minerals. (Comptes Rendus, vol. 144, 1912, p. 797, and Bull. Soc. franç, minér., vol. 31, 1908, pp. 218-312; vol. 33, 1910, p. 321; vol. 35, 1912, p. 84.) The first is isometric and comprises blomstrandite and two new species that I have called betafite and samiresite; these minerals crystalize in great yellow or greenish octahedrons; the second is orthorhombic and includes euxénite, samarskite, and the new mineral that I have named ampangabéite. We must add to it the tetragonal fergusonite.

3 The mineralogical characteristics of these pegmatites are its abundance of sodium and lithium bearing minerals; when mica exists it is no longer potash-mica, but lepidolite and zinwaldite rich in lithia. Biotite is common to two types of pegmatite, of which I have recently stated the different characteristics. (Comptes Rendus, vol. 155, 1912, p. 441.)

I have given in my Minéralogie de la France et de ses Colonies (vol. 4, p. 695) a detailed study, accompanied by numerous photographs, of these blendings of various colors, submitted with some interesting models in harmony with the ternary symmetry and occasionally with the hemimorphisms of the mineral • In the pegmatites with the blue beryl these tourmaline crystals are sometimes of colossal dimensions (more than a meter).

The beryl is common enough. It is of a pale rose or dark carmine color, so unusual that it is proposed to give to it a special name, that of "morganite."

Spodumene,' almost everywhere else epaque, is found in a limpid form, of a beautiful rose color with a tinge of lilac, accompanied by an exceptional brilliancy, and this variety, the "kunzite," forms a magnificent stone, rivaling the one which until then had been found only in California.

3

However, I must mention a garnet, the spessartite, supplying some orange-colored gems having a refraction as odd as it is strong, besides a mineral making, also, its first appearance as a precious stone, the danburite, which, once cut, is hard to distinguish from the yellow topaz of Brazil.

Often inclosed in pegmatite and without distinct crystal forms, all these minerals, with many others besides, show themselves in pockets of crystals, a description of which would not be out of place in a tale of the "Thousand and One Nights"; tiny grottos with marvelous walls illumined by the sparkling of thousands of crystals, and among them one does not know what to admire the most, the delicateness and perfection of the forms, the multiplicity and brilliancy of the faces, or the variety and richness of the colors.

While they may form, like the aquamarine, some prisms of great dimensions, or even the smallest crystals, but with faces of a wonderful clearness, like those from the pockets, or again some shapeless fragments, all the transparent minerals taken from the open quarries are carried each evening to the foreman, called the commander,

1 The beryl of Madagascar does not always have the simple composition (silicate of alumina and glucina) that has long been attributed to it; very frequently, above all in the lithia-bearing pegmatites, part of the glucina is replaced by some alkalies, of molecular weights more or less considerable (lithium, rubidium, caesium), and this substitution at once prevents the increase of density and that of the indices of refraction. This variation is continuous; it is not necessarily connected with the color, but the light beryls are most often blue or green, the heavy ones more often rose.

A knowledge of this property is very important in order to diagnose these precious stones, the density of which may vary from 2.70 to 2.90 and the indices in the following limits: ng-1.5818 to 1.6021, np=1.5756 to 1.5953, in the specimens studied up to the present time, and which does not constitute, perhaps, the extremes of that series. I should add in addition to this that the very dense beryls, instead of being lengthened near the vertical axis, as in the very light ones, are flattened near the base. I have discussed that question recently in the Bulletin de la Société française de minéralogie, volume 31, 1912, page 200, and in some previous articles.

2 This mineral belongs to the pyroxene group, of which it shows the crystals; it is a silicate of alumina and lithia.

3 The spessartite is an alumina and manganese garnet, containing a little lime; that orange color is special to Madagascar; it can be compared, but it is not identical with the spessartite of North Carolina. In the aquamarine beryl pegmatites some garnet is also found, but it is the almandine, red and opaque.

This mineral is a silico-borate of lime; I announced its existence in Madagascar (Bull, Soc. franç. minér., vol. 31, 1908, p. 314), from some crystals from the valley of the Sahatany.

• We should also mention among the minerals found in pegmatite apatite, rhodizite, and blomstrandite; as to crystalized minerals from pockets, they are quartz, microcline, albite, tourmaline, beryl, and lepidolite, to which we should add two new mineral species that I have called "bityite" (Comptes Rendus, vol. 146, 1908, p. 1367) and the "manandonite" (Bull. Soc. franç. minér., vol. 35, 1912).

In a few deposits the pegmatite is found intact and very hard. More often it is either kaolinized or lateritized, and in these two cases it has become soft enough to be quarried with the pickax or shovel; the gems can then be easily extracted. In many of the beds they work on éluvions, collecting the pegmatite in place or fallen to its immediate vicinity.