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. 16. The _cyanus_ of Pliny may have been our _cyanite_. 17. _Astrios_ agrees very well, as far as the description of Pliny goes, with the variety of felspar called _adularia_. 18. _Belioculus_ seems to have been our _catseye_. 19. _Lychnites_ was a violet-coloured stone, which became electric by heat. Unless it was a _blue tourmalin_, I do not know what it could be. 20. The _jasper_ of the ancients was probably the same as ours. 21. _Molochites_ may have been our _malachite_. The name comes from the Greek word μολοχη, _mallow_, or _marshmallow_. 22. Pliny considers _amber_ as the juice of a tree concreted into a solid form. The largest piece of it that he had ever seen weighed 13 lbs. Roman weight, which is nearly equivalent to 9¾ lbs. avoirdupois. _Indian amber_, of which he speaks, was probably _copal_, or some transparent resin. It may be dyed, he says, by means of _anchusa_ and the _fat of kids_. 23. _Lapis specularis_ was foliated sulphate of lime, or selenite.