The _Thyites_, according to Fuchsius, was a Turquoise; but Matthiolus is of a different opinion. Sprengel thinks it may have been a species of turquoise, although not the common one. Dr. Hill says it contains a small quantity of copper, which rendered it a valuable ingredient in collyria. It is prescribed for this purpose by Dioscorides. (v, 153.) The _Amiantus_ is composed of talc, calcareous and siliceous earth, clay, and a small proportion of iron. It is often confounded with the _Alumen plumosum_ of the ancients, to which it is compared by Dioscorides. He does not mention any medicinal use to which it was applied, but merely states of it that it was used for forming the _linum asbestinum_. (v, 155.) See further Harduin in Plin. H. N. (xxxvi, 31.) The _Sapphirus_ of the ancients is supposed by Beckmann to have been the Lapis lazuli. (History of Inventions.) This opinion is now pretty generally established, and yet there is a difficulty attending it; for the Arabians, in treating of the _Lapis lazuli_, do not quote the descriptions of the sapphirus given by Dioscorides and Galen, but apparently refer to the _cyanus_. Dioscorides recommends the sapphirus as an alexipharmic, and a remedy for internal ulcerations and diseases of the eyes. (v, 156.) Galen merely recommends it as an antidote to the stings of scorpions. Rhases, under the head of “Lapis lazuli,” quotes Dioscorides as saying of it that it promotes the growth of the eyelashes, that it restrains fungous flesh, is septic, caustic, and ulcerative; and Galen, as saying of it, that it has abstergent powers, with a moderate degree of attenuating and styptic virtues; that it may be mixed in collyria for the eyes, and especially for the eyelids when affected with sharp humours, which it represses, and also prevents the growth of the hairs. (Cont. l. ult. i, 404.) See also Serapion (c. 389); Averrhoes (Collig. v, 43); and Haly Abbas (Pract. ii, 45.) The _Calais_ of Pliny and the ancients is said by Dr. Hill to be the _Turquoise_, or _Gemma Turcica_, which consists principally of lime and iron. See the Thyites. The _Memphites_ contains bitumen and ethereal oil. It is the retinasphaltum of Mr. Hatchett, or retinite of Jameson. (Mineral, iii, 478.) According to Dioscorides, when rubbed smoothly upon places about to be burnt or cut, it renders them insensible without danger. (v, 157.) The _Selenites_ consists principally of a compact lamellated gypsum. According to Eustathius, it is the same as the _Lychnitis_, which Dionysius the geographer describes as resembling fire in lustre. (Orbis. Descrip. 328.) It is soft, pellucid, and colourless. Dioscorides describes it minutely, and mentions of it that it was given as a draught to epileptics, and used as a phylactery by women. He adds, that it was also appended to trees in order to make them keep their fruit. (v, 158.) Rhases, under the head of “lapis lunaris,” copies this chapter of Dioscorides. (Cont. l. ult. i, 405.)