Page:Madras Journal of Literature and Science, series 1, volume 6 (1837).djvu/412

384 rock. It forms whole hills, of which the long diameter extends from east to west. The structure of this rock is extremely hard, and in appearance it varies from a secondary sandstone to that of pure quartz.

This quartz-rock formation extends as far as Belgium, where we again meet with the amygdaloid. The undulating ground here, which is of inferior height to the hills of broken basalt, is composed of a red clay-iron-stone or laterite. It is sometimes of a yellowish colour, soft, and in a state of decomposition, from the action of the weather: in such instances it has much resemblance to iron rust. In either case it is hard and undulated, forming an aggregated rock which is used for building.

From Belgaum to Kittor we meet with numerous pieces of iron ore scattered over the surface of the ground. They are most abundant where the soil is red; and are chiefly to be met with near the hills lying south-east from Kittor. Some specimens of the ore are bubbled, having the appearance as if they had suddenly cooled while in a slate of fusion. From the mixed nature of the rocks found in this part of the country, quartz, iron-stone, and basalt, being indiscriminately huddled together, I am inclined to think that some strong convulsion of nature must have produced this at some time or other; and the generally bubbled appearance of the rocks warrants this conclusion. Specimens of black quartz are found among these rocks.

In the immediate vicinity of Kittor the structure of the rocks is coarse slaty. They are composed of alternate layers of quartz and iron ore, varying in thickness from the sixteenth-part of an inch to that of a whole, which gives the rock a striped appearance.

The effect which this rock produces on the magnetic needle is, however, the most extraordinary part of its nature. It has no inherent magnetic power, since it does not attract steel under any form; but when cut into a parallelogramical figure, of which two sides are longer than the other two, as here represented, it exhibits great power over the needle of a small pocket compass.

If the side be presented to the north pole, it repels the needle; but when brought round to the south pole, it attracts it. When the side is presented to the north pole, the effect is vice versa; and if the stone be moved circularly over the glass of the compass, the needle is set in motion.

It would appear, therefore, that this rock possesses polarity, but does not exhibit any magnetic power in attracting simple steel. The ore it contains is probably magnetic iron ore; and the well-ascertained