Page:Transactions of the Geological Society, 1st series, vol. 4.djvu/237

 accordingly I have laid before the Society some small specimens found there by Lord Gray's workmen in removing earth at the foot of one of the precipices. It forms veins of different dimensions in the fragments of rock, with which it is intimately united: it is of a finer green colour than that which is found in Rum, but none of the specimens which I procured contain the red spots for which this mineral is principally valued. It sometimes is associated with a green quartz, coloured apparently by the same material, the more transparent parts having the aspect of plasma, which not improbably owes its colour to chlorite. I did not succeed in finding this mineral in the face of the rock from which these specimens appear to have been detached, but among the agate pebbles there to be seen I obtained some which present appearances illustrative of its composition. These pebbles are frequently incrusted with a coating of chlorite, and in those to which I allude the chlorite penetrates the external part of the agate to the eighth of an inch, so as to convert the outer crust into heliotrope. I may here also add that I have observed this mineral among the agates found in Ayrshire, and that it occurs in the island of Mull, where it forms spheroidal nodules in basalt, so that it is not rare in Scotland. When I say that zeolites are not found in Kinnoul, I ought to add, that I picked up one loose and had specimen of red stilbite.

On the top of the great mass of trap which I have now described, there is to be seen a portion of a bed of conglomerate, consisting of trap pebbles imbedded in a cement of the same nature, a rock improperly designated by the name of trap tuff. The origin of this rock is not easily explained, but I must defer the remarks that might be offered on this subject to some future opportunity.

The last and most remarkable circumstance occurring in Kinnoul is that of an extensive range of those junctions with other rocks