BUTTON-STONE, in Natural History, a kind of figured stone, so denominated from its resembling the button of a garment. Dr Hook gives the figure of three sorts of button-stones, which seem to have been nothing else but the filling up of three several sorts of shells. They are all of them very hard flints; and have this in common, that they consist of two bodies, which seem to have been the filling up of two holes or vents in the shell. Dr Plot describes a species finely striated from the top, after the manner of some hair buttons. This name is also given to a peculiar species of slate found in the marquisate of Barchinona, in a mountain called Fichtelberg; which is extremely different from the common sorts of slate, in that it runs with great ease into glass in five or six hours time, without the addition of any salt or other foreign substance, to promote its vitrification, as other stones require. It contains in
itself all the principles of glass, and really has mixed in its substance the things necessary to be added to promote the fusion of other stony bodies. The Swedes and Germans make buttons of the glass produced from it, which is very black and shining, and it has hence its name button-stone. They make several other things also of this glass, as the handles of knives and the like, and send a large quantity of it unwrought in round cakes, as it cools from the fusion, into Holland.