ASTERIA is also the name of a gem, usually called the cat's eye, or oculus cati. It is a very singular and very beautiful stone, and somewhat approaches to the nature of the opal, in having a bright enclosed colour, which seems to be lodged deep in the body of the stone, and shifts about, as it is moved, in various directions; but it differs from the opal in all other particulars, but, above all, in its want of the great variety of colours seen in that gem, and in its superior hardness. It is usually found between the size of a pea, and the breadth of a sixpence; and is almost always of a semicircular form, broad and flat at the bottom, and rounded and convex at the top; it is naturally smooth and polished, and is usually worn with its natural polish. It has only two colours, a pale brown and a white; the brown seeming the ground, and the white playing about in it, as the fire-colour in the opal. It is considerably hard, and will take a fine polish, but is usually worn with its native shape and smoothness. It is found in the East and West Indies, and in Europe. The island of Borneo affords some very fine ones, but they are usually small; they are very common in the sands of rivers in New Spain; and in Bohemia they are not unfrequently found immersed in the same masses of jasper with the opal.