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.
24. Pyrites had the same meaning among the ancients that it has among the moderns; at least as far as iron pyrites or bisulphuret of iron is concerned. Pliny describes two kind of pyrites; namely, the white (arsenical pyrites), and the yellow (iron pyrites). It was used for striking fire with steel, in order to kindle tinder. Hence the name pyrites or firestone.
25. Gagates, from the account given of it by Pliny, was obviously pit-coal or jet.