Molybdjena. ®57 granite of the oldeft formation, in the mountains of Silefia, thofe of Sweden, and it is faid alfo in the primitive granite of Cruachan in this country. It alfo occurs, along with tinftone, wolfram and tungften, in the Saxon and Bohemian tin forma tion. That formation lies in granite, which, from its chara&ers, appears to belong to the neweft gra nite formation. This metal is alfo found in the famous iron-mines of Norway ; but we know fo little of the geognoftic relations of the rocks in * t thefe diftri&s, that we cannot as yet determine with any certainty the exadt date of the molyb- dena they contain. In Glenelg, I obferved very fmall portions of it imbedded in chlorite-flate. Combined with oxygen, it occurs in fmall quantity in the form of molybdat of lead (yellow lead-ore), in the oldeft floetz-limeftone. 2. Menacbine, the Titanium of chemifts. This metal appears to be next in age to molybdena, becaufe one of its fpecies, Rutile, occurs «in thofe drufy cavities which are not unfrequent in granite mountains of the higheft antiquity, lying in or up on the rock-cryftal, adularia, and foliated chlorite, with which thefe cavities are lined. The fame fpecies occurs alfo imbedded in mica-flate and fienite. Dr Reufs, the Bohemian inincralogift, affirms that he obferved it in the neweft floetz-trap formation, imbedded in bafalt; and this obferva- tion is ftrengthened by the difcovery of Mr Gregor, Vol. III. K k who