The following substances have, for the most part, passed under the names here assigned to them; but they are themselves either ill-determined, or doubtful species: in some cases the name has been attached to certainly more than one specifically-distinct substance.

From Quiraing in Skye. It occurs in layers of an inch or two in thickness, among the amygdaloids. It is usually of a deep-red colour and has a greasy lustre, but is sometimes earthy and dull.

It falls to pieces in water, and may, by this property, and its uniformly dense structure, be distinguished from the red massive mesolite which sometimes occurs along with it.