Touchstones would appear, from their make, to have been worn about the person, several being pierced with a hole, seemingly for attachment of a string. Sir W. Wilde remarks that they have been found both flat and four-sided, and with and without perforation. They are formed generally of black Lydian stone or of jasper, either material being suitable for gold-testing. Lydian stone, or black chert, is “an impure flint, found in the central portions of the carboniferous limestone of Ireland, and at the base of the Kilkenny coal formation. It is of a dull dark colour, approaching to black; is more opaque, brittle, and stone-like, than flint; never possesses the same translucency, and does not so readily chip into conchoidal fragments: but, next to flint, it is one of the hardest of the siliceous rocks, and hence was used occasionally for forming tools and weapons by the inhabitants of those districts where flint was rare. Lydian stone, ‘Lapis Lydius,’ or, ‘Lapis Hibernicus,’ as it was denominated by the old Dutch writer De Boot, so long ago as 1647, is the true touchstone of the ancients.” [Illustration: Fig. 156. Pipe-clay Crucible.] Few ornaments of silver, and still fewer of gold, have been brought to light in crannogs, the antiquities of which consist mainly of the more homely class of bone, bronze, and iron articles for personal adornment; yet numerous gold ornaments have doubtless been discovered, but remained unrecorded, from fear of detection on the part of the finder, before the Treasury Minute respecting “Treasure Trove” came into operation. Antique articles of gold have been turned up in the bogs of Ireland, and in various parts of the country. Is it likely that the inhabitants of “island fortresses” should alone be devoid of the precious metal, especially as in them have been found both small earthen crucibles--so diminutive as to have been useful only for gold or silver smelting,--and also small pipe-clay cupels for refining purposes, like those used in the present day for the assay of gold and silver? Fig. 156 represents a pipe-clay crucible from the crannog of Lagore, 2 inches broad, and 1 inch high. A well authenticated instance of the discovery of the precious metal in a crannog, was that of “several gold pins,” at Loughtamand, county Antrim;[142] and, in the autumn of 1870, a beautiful, almost unique, specimen of early Irish art came to light on the site of the former lake dwelling of Lough Ravel, county Antrim. The accompanying woodcut is the size of the original. This silver brooch, or fibula, represents two bird-headed serpents joined together: both sides of the ornament are alike; the silver is slightly thinner than a shilling piece; the pin is missing. In the design there seems to be a resemblance to some of the initial letters in the “Book of Kells,” and other early Irish MSS., so that its probable age is not later than the tenth century.[143] [Illustration: Fig. 157.--Silver Brooch from the Crannog of Lough Ravel.]