Texture of Ore-Veins.—The varying texture of ore-veins referred to towards the end of Prof. Cotta's memoir may not be intelligible without a short explanation. We find that the two extreme textures of veins may be classed as (1) a compact texture, and (2) a banded or layer-like texture, both of these of course having many varieties, and passing into each other. The first is often characterized by a breccia-texture, that is by containing fragmenta—often very numerous—of the neighbouring rock. The figure below shows an extreme case of this breccia-vein; and also the peculiar manner in which these fragments are usually surrounded by some crystallized mineral, marked by the axes of the crystals all radiating as if from a centre.