Page:Transactions of the Geological Society, 1st series, vol. 3.djvu/408

 striking feature in the neighbouring country. Blocks of the same species of rock are scattered about in different parts of the hill and in its vicinity.

This rock is of dark bottle green colour. All the specimens of it do not possess an uniform degree of hardness: they vary also in respect of fracture. The harder species frequently assumes that wavy and polished exterior surface which characterizes the magnesia stones. It is sufficiently hard to scratch glass. It has an uneven and sharp edged or splintery fracture, which exhibits no lustre. Upon examination of its surface with a pocket microscope, it appears to consist of a very fine-grained uncrystallized substance of a blackish green colour, interspersed with thin laminæ of precious serpentine of a green colour. The rock of the softer species seems to be composed of these two substances also. It has a few small greyish white specks scattered over it: these are occasioned by some softer substance imbedded in it. I am inclined to think that this substance is compact tremolite. The softer species of rock may be scratched with the nail. It has an uneven fracture, inclining to earthy. This rock abounds with iron, insomuch that the magnet is enabled to attract very small particles of it. It resists a very strong flame of the blowpipe without being fused. The line edges however of the harder species seem to yield a little to its action.

In the side of the hill, below the ridge of rock, a quarry is opened for the purpose of supplying the neighbouring road with stones. Here the rock is laid bare in large masses. It is accompanied in some places with asbest, and also with a line white earth, which appears from the filaments which are mixed with it, to consist of asbest broken down in a state of partial decomposition.