Roofing Slate.

Very good slate has been discovered in the Otepopo district, on a branch of the Kauroo River. These slates belong to the Kakanui formation, and it is probable that they may also occur at other places situated in the area occupied by this formation (see map); but I doubt if they are likely to be found in a more accessible place than the present discovery.

These slates split very freely, but the cleavage is not true slaty cleavage, for it evidently follows the plane of the bedding. On the other hand it is not ordinary lamination. It appears to me to be a spurious cleavage induced along the original plane of bedding by vertical pressure when the slates were undergoing a slight metamorphism. But although these slates are not equal to the best Welsh slates for purposes that require a ground or polished surface, they will, I think, be found nearly equal to them for roofing. Their page 112hardness is quite sufficient, and that they will stand the weather perfectly is proved by the excellent state of preservation of surfaces long exposed to the weather. I saw large blocks, looking as sharp and fresh as if they had been just detatched from the rock, which were almost buried in the vegetation that had grown up around them; while at the same time the very small amount of vegetation (confined to lichens) growing on the exposed surfaces shew that they do not readily absorb moisture. They will also stand well a hole being knocked through them with a slater’s hammer, not a single one splitting that was tried. The waste in working a slate quarry is generally supposed to be five tons to one of marketable slate, and it is therefore very important for the economical working of a quarry that it should be so situated that this large waste can be got rid of without much expense. This can be easily secured in the present locality.