Page:Transactions of the Geological Society, 1st series, vol. 3.djvu/295

 to a more minute division, many of them may perhaps also be in a state of solution. On a small scale indeed examples of stony matters so formed are not wanting in nature. Such are the hard deposits of calcareous and other matters in water pipes, and in vessels at no greater temperature than that of boiling water. It is easy to see in the case of the semi-indurated strata, and of the soft minerals above described, how the further abstraction of the water in which these affinities were first brought into action, may by increasing them in consequence of the nearer approximation of the earthy particles, induce that stony hardness which these substances acquire in drying.

A third and more beautiful variety of tremolite is also found here. This like the last forms thin beds interposed between those of the marble, and occasionally also entering as a constituent part into the stone. It is that well known variety which so much resembles spun glass, that this comparison forms the best description that can be given of it. It is generally of a pure white colour, and is radiated in stellated forms varying from an inch to two feet in diameter, and exhibiting specimens of uncommon magnificence. I could not perceive that any of the specimens of this variety were so decidedly flexible as the latter, although they were taken from the bottom of the river, but there was still a very sensible difference in their power of cutting the hands and entering into the skin when first taken up, and after they had been kept for a few days. More rarely the same fibrous and silky variety is found passing through all the shades of colour, from a pale to a very dark sea-green, and these latter specimens are particularly marked by the I crowded and beautiful groups of their small stellated radiations.

At no great distance from these beds and in a similar position, a fourth and hitherto undescribed variety is also found, constituting a