Prof. T. O. Bonnet/ — Ligurian and Tuscan Serpentines. 365 



mountains ; so I procured a guide, and set off to visit them. The 

 road passed above the quarries already mentioned, and wound round 

 the upper part of the headland north of Levanto, till it turned up 

 the ravine which descends on Bonasola. The country is for the 

 most part wild and uncultivated — a waste of serpentine crags and 

 boulders, thinly overgrown by brushwood, myrtles, and scattered 

 pines. The serpentine is often very rotten, but masses also occur where 

 the rock is well preserved. In general character it resembles the 

 Lizard serpentine ; joints are frequent and irregular, but sharp, often 

 coated with white steatite; the outer surface turns brown in weather- 

 ing, and often becomes rough. In one place the weathered rock 

 exhibited a fairly perfect spheroidal structure, which, so far as my 

 experience goes, is not common in serpentine. About a mile below 

 the first quarry I noted a mass of altered sedimentary rock, six or 

 seven yards long, apparently included in the serpentine. It is of a 

 claret-red colour, is rather harder than calcite, and is evidently 

 an indurated argillaceous rock. A coarse gabbro of the usual 

 character occurs some distance further on. Apparently it is intru- 

 sive in the serpentine, but both are so rotten that it is not easy to 

 ascertain their relations. 



The first quarry is high up in the mountains, probably not less 

 than 800 feet above the sea, and the surrounding summits rise some 

 hundreds of feet higher, all being serpentine. This quarry affords 

 a good oppoi'tunity of examining the breccia, as it is some forty 

 yards long and perhaps twelve deep. The beautiful structure and 

 colour is easily brought out by dashing a little water on the surface. 

 There is another quarry about ten minutes' walk higher up, in 

 which a similar rock occurs, and there are two or three more in the 

 vicinity, so that there must be a considerable tract of this breccia. 

 The result of my examinations, both in the quarry and of the great 

 blocks at Levanto (which were hardly less instructive), may be thus 

 summed up). The serpentine is of the ordinary type, but a red 

 variety is as common, or perhaps commoner than the dark green. 

 The cementing material is crystalline calcite. The rock is evidently 

 not an agglomerate, but has been brecciated in situ. For example, 

 one block might be quarried which would be a mass of serpentine, 

 only traversed by a few cracks which had been filled up by infil- 

 trated calcite. Another would show fragments smaller, and some- 

 times displaced a little, the calcite being more abundant, and the 

 spaces occupied by it larger. Another would give no clue to its 

 origin, but would be simply a breccia of fragments of serpentine 

 cemented by calcite, which would now and then seem to form 

 almost half the rock. Parts exhibit an intimate mixture of pulverized 

 serpentine and calcite, and here and there are filmy patches of 

 a serpentinous mineral. Yet every gradation, from the almost un- 

 broken rock to this complete " smash," may be traced. One face of 

 rock in the lower quarry exhibited it perfectly in a space of about 

 four yards. 



I have examined microscopically slides cut respectively from a 

 specimen greatly brecciated and from one merely veined with calcite. 



