§ 7 Of Paragon (Touchstone)48
A kind of black stone, called paragon, is likewise quarried in Egypt and also in some parts of Greece. It is so named because it forms a test for trying gold; the workman rubs the gold on this stone and discerns its colour, and on this account, used as it is for comparing or testing, it comes to be named paragon, or indexstone (a). Of this there is another variety, with a different grain and colour, for it has, almost but not quite, the tint of the mulberry, and does not lend itself readily to the tool. It was used by the ancients for some of those sphinxes and other animals seen in various places in Rome, and for a figure of greater size, a hermaphrodite in Parione,49 alongside of another most beautiful statue of porphyry.50 This stone is hard to carve, but is extraordinarily beautiful and takes a wonderful polish (b). The same sort is also to be found in Tuscany, in the hills of Prato, ten miles distant from Florence (c), and in the mountains of Carrara. On modern tombs many sarcophagi and repositories for the dead are to be seen of it; for example, in the principal chapel in the Carmine at Florence, where is the tomb of Piero Soderini (although he is not within it) made of this stone, and a canopy too of this same Prato touchstone, so well finished and so lustrous that it looks like a piece of satin rather than a cut and polished stone (d). Thus again, in the facing which covers the outside of the church of Santa Maria del Fiore in Florence, all over the building, there is a different kind of black marble (e) and red marble (f), but all worked in the same manner.