6. The chrysolite of Pliny is supposed to be our topaz: but we have no other evidence of this than the opinion of M. Du Tems.
7. Asteria of Pliny is supposed by Saussure to be our sapphire. The lustre described by Pliny agrees with this opinion. The stone is said to have been very hard and colourless.
8. Opalus seems to have been our opal. It is called, Pliny says, pæderos by many, on account of its beauty. The Indians called it sangenon.
9. Obsidian was the same as the mineral to which we give that name. It was so called because a Roman named Obsidianus first brought it from Egypt. I have a piece of obsidian, which the late Mr. Salt brought from the locality specified by Pliny, and which possesses all the characters of that mineral in its purest state.
10. Sarda was the name of carnelian, so called because it was first found near Sardis. The sardonyx was also another name for carnelian.
11. Onyx was a name sometimes given to a rock, gypsum; sometimes it was a light-coloured chalcedony. The Latin name for chalcedony was carchedonius, so called because Carthage was the place where this mineral was exposed to sale. The Greek name for Carthage was Καρχηδων (carchedon).
12. Carbunculus was the garnet; and anthrax was a name for another variety of the same mineral.
13. The oriental amethyst of Pliny was probably a sapphire. The fourth species of amethyst described by Pliny, seems to have been our amethyst. Pliny derives the name from α (a) and μυθη (mythe), wine, because it has not quite the colour of wine. But the common derivation is from α and μυθυω, to intoxicate, because it was used as an amulet to prevent intoxication.
14. The sapphire is described by Pliny as always opaque, and as unfit for engraving on. We do not know what it was.
15. The hyacinth of Pliny is equally unknown. From its name it was obviously of a blue colour. Our hyacinth has a reddish-brown colour, and a great deal of hardness and lustre.