OSTEOCOLLA, in natural history, though supposed by many to be an earth, is truly a crustated kind of spar debased by earth, and therefore not transparent. It is usually found coating over vegetables, or other bodies, in form of incrustations; so that the true osteocolla is a tubular crustaceous spar of a very foul and coarse texture; and carries with it much more the appearance of a marl than of a species of spar. The masses of osteocolla, though regularly of the same figure, are very different in size; some of them not being thicker than a crow quill, while others are five and six inches in diameter; it is always, however, of a tubular figure, and a wrinkled rough surface. Osteocolla is frequent in Germany; where it is found buried near the surface of the earth, sometimes in strata of sand, but more frequently among marls: it should be chosen, for use, the purest that can be had, of a pale brown colour, and of a tolerably firm and close texture.—It has long been famous for bringing on a calculus in fractured bones; its name, osteocolla, signifies "bone-glue," or the "bone-binder." It is also recommended as a diuretic, and as good in the fluor albus; but the present practice has rejected it.