Page:The parochial history of Cornwall.djvu/68

26 Launceston road, hornblend slate prevails, and affords a very fertile soil. Descending the hill to Pellaphant, masses of compact rock protrude from beneath the soil. They are composed of compact felspar, aggregated with lamellar hornblend, forming a kind of sienite. But the most interesting object in this parish is to be found a little to the north of this last place, on the side of the hill sloping down to the river Inny. It is a magnesian rock, and it is quarried for building-stones, yielding large blocks, which are sufficiently soft at the time of their being raised, to allow of their being cut through by a common handsaw. A considerable quantity of this stone has been used in building a very large house, denominated a cottage by the Duke of Bedford, at Ensleigh, on the eastern bank of the Tamma. The stone appears, however, to have one bad quality: the surface, after a slight disintegration from exposure to the atmosphere, becomes covered over with ocherous spots, owing to the presence of a scaly mineral resembling diallage, which is disseminated through the rock. This magnesian rock has all the characters of pitstones, the lapis ollaris of the ancients; and it is a curious circumstance, that on opening some old workings near this place, several antique vessels were found resembling pipkins and shallow pans made out of this material.

The immediate connection of this bed of ollareous serpentine with the adjacent rocks, is not disclosed; but it is succeeded by talc ore, slate, and limestone, on the other side of the river.

St. Anthony in Powder is situate in the hundred of Powder; and hath upon the east Gerance and St. Just; north, Carike road, or part of Falmouth harbour; upon the south and west the British Channel.