A TRIP TO MADAGASCAR, THE COUNTRY OF BERYLS.1

By A. LACROIX,

Membre de l'Institut de France.

Madagascar, the land long full of mystery and of fabulous legends, has ever since it was opened up to the world been noted for its mineral riches.

3

The second Frenchman who landed on the island, Capt. Jean Fonteneau, called Alphonse le Saintongeois, declared that he found precious stones there in 1547.2 One hundred years later, in 1658, Flacourt speaks of topazes, aquamarines, emeralds, rubies, and sapphires, and shows on his map the places where one could find those marvelous masses of rock crystal, limpid as the purest water, which have ever since been sought after for ornamentation and for optical use. Up to the middle of the last century every traveler who wrote about the "Grand Ile" did not fail to note the great abundance of gems there, although many attempts at their practical utilization, made in the seventeenth and eighteenth centuries by the French East India Co., had lamentably failed.

When the period of scientific exploration commenced, some fearless pioneers, in the front rank of whom I would place our colleague, M. Alfred Grandidier, quickly made known the principal features, so peculiar, of its flora and fauna, but all that concerned its mineralogy was hardly glanced at, for a reason that I will explain. In order to protect its mineral resources the Government of Madagascar had instituted a system as ingenious as it was efficient. One penalty only-and that was death-stopped all mineral research by for

1 Lecture at the annual meeting of the Cinq Académies de l'Institut de France (Oct. 25, 1912). Translated by permission from La Géographie. Bulletin of the Geographical Society of Paris, Nov. 15, 1912. * Voyages adventureux du capitaine Jean-Alphonse-le-Saintongeois, Paris, 1559 (reprinted in Coll. ouvr. anc. Madag. by A. and G. Grandidier, vol. 1, pp. 92-95).

Histoire de la Grande Isle de Madagascar, Paris, 1658.

♦ This mineral was found in the rivers of the eastern coast, to the north of the Bay of Antongil and notably in the region of Vohemar. I have specified (Comptes Rendus de l'Acad. des Sciences, Paris, vol. 155, 1912, p. 491) the conditions under which this mineral abounds on the high plateaus. The beds actually worked in place are pockets of crystals in the metamorphosed quartzites.

Notably: (Du Bois) Les voyages faits par le sieur D. B. aux iles Dauphine ou Madagascar et Bourbon ou Mascarenne, és annees 1669-70, 71 et 72, Paris, 1674, 151. Souchu de Rennefort, Histoire des Indes orientales, Leide, 1688, 173. De la Haye et Caron, Journal du voyage des Grandes Indes, Paris, 1688.

eigners. Since the French occupation of the island, the prospectors have taken their revenge. The map of the "Service des Mines," on which is recorded the sites for permits for research, resembles a swarm of ants.

Among the treasures that this remarkable activity has drawn from the earth, precious stones, along with gold, must be placed as the principal object of exploitation. The conjectures of ancient voyagers have been realized, but I should say that the mineral deposits now worked are not at all those which they believed they had discovered. They knew only of those near the mouths of the rivers of the eastern coast and in the neighborhood of Fort Dauphin, there where modern research has so far brought to light only some quartz and poor garnets, unfit for any economic use. The real deposits are

found elsewhere.

Official statistics show that in 1911 there were exported from Madagascar 470 kilograms of stones ready to be cut; it is a good omen for the future of so new an industry. I was at its birth. I have followed its rapid strides while there has been unearthed material of a scientific interest of the first order. Thus in the course of a recent mission, to which I was attached, I undertook, among other subjects, to study on the spot all the mineral occurrences that might yield the least gem. I now propose to outline what I saw.

1 It is shown by the following references that it was these minerals that those early explorers had seen: In 1666 François Martin (the founder of Pondichéry) says that the passengers of the Vierge du Bon Port brought a quantity of topazes, amethysts, and other colored stones that they had found at Fort Dauphin. "That has been a fancy of the French who were in the island, but they have not been appreciated in France because they were found too fragile." (Archives nationales, MS.)

In 1668, De Faye, director of commerce of the East India Co., wrote "that the company has been very much undeceived on the subject of some precious stones of which wonderful things had been promised him and for which in India they had not given a sou per thousand [some topazes and amethysts from the Itapere River (Fort Dauphin)]. (Arch. Min. Colonies, Manuscripts.)

This last story is confirmed by De la Haye (op. cit., 91). "Director Caron, arriving at Surate, offered some to the governor of the city, who refused them, smiling at the gift, which, however, was nine of the most beautiful stones that had yet been seen and the smallest as large as a quail's egg, and all cut in various shapes. They were shown to several jewelers, who were pressed to state their value, and none estimated higher than 9 rupees for the most beautiful and 27 for all the others."

• The first specimens received at the museum were a beautiful crystal of rubellite, some small sapphires and zircons, given in 1891 by A. Grandidier. (Jannettaz. Bull. Soc. franç. minér., vol. 14, 1891, p. 66.) The first specimens reported in France with the precise indications of their localities were given to me by E. Gautier; I described them in 1899 (Bull. Muséum, p. 318); a little later Mr. Villiaume sent me some tour. malines found by him to the west of Mount Bity.

I believe that I was the first to have these precious stones of Madagascar cut in a systematic fashion, following the exposition made at the museum at the time of the expedition; there were some chrysoberyls, some garnets, some corundums, and topazes, etc., from the alluvia of Belambo near Mevatanana and brought back by M. Suberbie. I afterwards exhibited in the Gallery of Mineralogy a fine series of yellow and brown tourmalines that I had had cut with the aid of patterns from the region of Tsilaisina, that Mr. Garnier-Mouton had sent me, who was then chief of the Province of Betafo.

I have described these materials in numerous notes and memoirs, particularly in my Minéralogie de la France et de ses Colonies, vols. 1-4, 1893-1900, in the article Minéralogie, in Madagascar au XX siecle, 1902, pp. 65-107, then in the Comptes Rendus de l'Ac. des Sciences and in the Bulletin de la Société française de Minéralogie from 1908 to 1912. See also the notes of M. Mouneyres and of M. Dabren (showing some results of the mission Villierme) in the Bulletin de l'Académie malgache, vol. 4, 1905, and in the Bulletin économique de Madagascar, 1906, besides those of MM. Dupare, Wunder and Sabot in the Bulletin de la Société française de Minéralogie, 1910-1911, in the Archives and the Memoires de la Société des Sciences physiques et naturelles de Genève, 1910.

It is necessary first of all to understand what we mean by a precious stone. Mineralogists classify minerals in the first place according to their chemical composition, then they determine from the form of the crystals how to establish subdivisions of a second order; therefore precious stones are, from every point of view, chemical; a simple element, oxides, aluminates, silicates, and many other combinations. All the modalities that can form crystalline symmetry are found represented there. It is not then the question of a natural family but of an artificial grouping.

To be a precious stone a mineral must unite a number of qualifications. It must be transparent, of a fine water; that is, very limpid. It should have a strong, clear color; hence, the doubtful tints, the halftones dear to painters, those which form the charm of certain flowers and the adornment of many animals, are not in favor. The mineral should be very brilliant, which depends upon two optical properties, dispersion and refraction; this last is dependent on density; therefore precious stones are more or less heavy. Finally, it must be hard, so as to take and hold a fine polish. The more a stone unites these qualities in a high degree, the more readily does it hold a high place in the realm of gems, a place which in addition to this is influenced by its comparatively great rarity.

To these intrinsic properties of the stone, we should, however, add something exterior to it that escapes the analysis of a mineralogist, for it is nothing less than feminine fancy, changing with the fashion. Thus, thanks to the favor which artistic jewels now enjoy, these stones, so correctly called "fancy," until lately so neglected, are each day more and more sought after. Madagascar should not complain, for these are the stones that most of all adorn her jewel case.

The definition which I am going to give may be exact; it is not, however, a general one. There are, in fact, some minerals which are neither limpid, nor clear, nor dense, nor hard, and yet are considered as precious stones. Such is the opaque turquoise, which owes its popularity to its beautiful delicate blue color; such is the opal,' which takes the charm of its beauty from the warm reflections that play about in its semitransparency.

A mineral which may constitute a gem, and sometimes of the highest value, is found not alone in its precious form. At Madagascar even corundum forms transparent sapphires, the value of which is estimated by the carat of 200 milligrams, and besides some enormous

1 The opal is also found in Madagascar, but it is not yet quarried; in the phonolite trachyte, coming from the south of Faratsiho, it constitutes very small veins, which possess reflections equal to those of the opal of Hungary and also some small veins which recall the fire opal, but with a tint more brown than red. I visited this deposit but collected only small fragments.

opaque crystals which are exported by the ton and utilized only in the abrasive industry.1

On the other hand, the list of gems is not definitely closed, for from time to time, following the discovery of a new deposit, the list is increased by the name of a mineral until then considered a mere pebble, because though possessing some of the qualities enumerated above, it has been lacking in transparency or in a pleasing color. Madagascar furnishes some examples of this. One of the most common constituents of the rocks which form the granite mountains of all countries-potash feldspar-has been found in a locality lost in the south (Itrongahy, about midway between Betroka and Benenitra) in crystals of an admirable limpidity, set off by a yellow color as warm as it was unusual and which gave it the appearance of golden beryl. Very near there, scattered through the soil, were found some fragments of a species of mineral, the name of which has never been heard by any of you, the "kornerupine.

Instead of forming grayish and opaque rods, as in the single deposit in Greenland, where until recently it had only been found, it constitutes a transparent, sea-green stone slightly recalling certain aquamarines but with an incomparably superior brilliancy.

Up to the present time no diamonds have been found in Madagascar, but nearly all the other gems occur there in great abundance.

Many of the minerals are seen in their original matrix, others are gathered in the alluvium resulting from the breaking up of their veinstone in place, while still others are a part of the alluvium accumulated by the work of streams.

The Grand Ile is made up principally of a basement of ancient rocks, eruptive and metamorphic, ending abruptly on the eastern side in high cliffs which are separated from the Indian Ocean by a narrow plain, low and sandy, while toward, the west the island terminates in a way no less abrupt, serving as a buttress for some sedimentary formations which come to an end in the Mozambique Channel. All the deposits of precious stones are located in the central ridge and particularly on the high plateaus that crown the island.

One of the principal attractions of a trip to Madagascar is the contrasts encountered at every step, contrasts due to nature, contrasts

1 I have shown that this corundum which abounds eastward from the meridian of Tananarive is formed in mica schists in connection with granite. (Comptes Rendus de l'Acad. des Sciences, vol. 154, 1912, p. 797.) There were exported in 1911, 150 tons, and this quantity will without doubt be doubled in 1912. Its hardness (6) is less than that of the beryl, likewise the density (2.55 to 2.60) and also its refraction (ng=1.5253, Nm-1.5248, np=1.5197).

3 Kornerupine is a magnesium aluminium silicate. Once cut, it is distinguished from the aquamarine as well as from the green andalusite of Brazil by its very great density (3.27) and especially by its refraction (ng-1.6742, nm-1.6733, np=1.6613). (A. Lacroix, Comptes Rendus, vol. 155, 1912, p. 675.) A variety named prismatine has been found in the granulite of Saxe, but it is formed only of little grayish rods not transparent.

The feldspar of Itrongahy is accompanied by crystals of limpid diopside, specimens of which of a bottle green color form a very pretty gem. Some violet zircons and green apatite might also be cut.