"For a very long time past," says M. Fournet, "the caves of Mentone had been known to the inhabitants of the district, on account of the accumulation of _débris_ contained in them, a boxful of which were sent to Paris, before 1848, by the Prince of Monaco; the contents of it, however, were never subjected to any proper explanation. Since this date, M. Grand, of Lyons, to whom I am indebted for a collection of specimens from these caves, carefully made several excavations, by which he was enabled to ascertain that the most remarkable objects are only to be met with at a certain depth in the clayey deposit with which the soil of these caves is covered. All the instruments are rough and rudimentary in their character, and must, consequently, be assigned to the first commencement of the art. Nevertheless, among the flints some agates were found, which, in my opinion, certainly came from the neighbourhood of Frejus; and with them also some pieces of hyaline quartz in the shape of prisms terminated by their two ordinary pyramids. We have a right to suppose that these crystals, which resembled the _Meylan diamonds_ found near Grenoble, did not come there by chance, and that their sharp points, when fixed in a handle and acting as drills, were used for boring holes in stone." Flint was not, however, the only substance used during this epoch in the manufacture of stone-hatchets, instruments and tools. In the caves of France, Belgium and Denmark a considerable number of hatchets have been found, made of gneiss, diorite, ophite, fibrolite, jade, and various other very hard mineral substances, which were well adapted to the purpose required and the use to which they were put. Among the most remarkable we may mention several jade hatchets which were found in the department of Gers, and ornamented with small hooks on each side of the edge. One of these beautiful jade hatchets (fig. 110), the delineation of which is taken from the specimen in the Museum of Saint-Germain, was found in the department of Seine-et-Oise; it has a sculptured ridge in the middle of each face. [Illustration: Fig. 110.--Polished Jade Hatchet in the Museum of Saint-Germain.] But neither flint, gneiss, nor diorite exist in every country. For these stones some less hard substance was then substituted. In Switzerland the instruments and tools were generally made of pebbles which had been drifted down by the streams. They were fashioned by breaking them with other stones, by rubbing them on sandstone, or by sawing them with toothed blades of flint according to their cohesive nature. In some localities also objects of large size were made of serpentine, basalts, lavas, jades, and other rocks chosen on account of their extreme cohesiveness.