376 PHYSIOGRAPHY. CLASS II. 



Before the blowpipe the yellow varieties do not change 

 their colour ; all the rest become yellow. They intumesce 

 a little, and melt on the edges into a dark-coloured enamel. 

 They are soluble in heated nitric acid, and leave a siliceous 

 residue. 



3. Prismatic Titanium-ore occurs in small nodules or 

 crystals imbedded in gneiss, and beds of syenite and other 

 trap-rocks, belonging to them, or also to more recent classes 

 of mountains. It is met with in metalliferous beds with 

 ores of iron, several species of Augite-spar and Feld-spar, 

 &c., and likewise in those veins which traverse primitive 

 rocks, and which are considered as the most ancient produc- 

 tions of that kind, as they consist of the same species as 

 these rocks themselves. 



4. Prismatic Titanium-ore occurs in several districts 

 of the Saualpe in Carinthia, imbedded in coarse-grain- 

 ed gneiss. At Hafnerzell in the district of Passau it 

 occurs in a bed in gneiss, consisting almost entirely of 

 Augite-spars and Feld-spars, at Windisch-Kappel in Ca- 

 rinthia, and near Dresden in Saxony, in similarly com- 

 pound rocks of a newer date. In beds of iron-ore it occurs 

 particularly at Arendal in Norway ; in veins at St Gothard 

 in Switzerland, in the Felberthal in Salzburg, and in many 

 other places in the Alps. It is found, besides, in many 

 countries, as almost every syenite contains small crystals 

 of it ; for instance, the variety from Strontian and other 

 places in Scotland. 



. PERITOMOUS TITANIUM-ORE. 



Prismato-Pyramidal Titanium-Ore. JAM. Syst. Vol. III. 

 p. 128. Man. p. 234. Titanite. Nigrine. PHILL. p. 258. 

 259. Rutil. Nigrin. WERN. Hoffm. H. B. IV. 1. 

 S. 252. Syst. p. 26. Eisentitan ? Rutil. HAUSM. I. 

 S. 318. 319. Rutil. LEONH. S. 147. Titane oxyde'. 

 HAUY. Traite', T. IV. p. 296. Tabl. conip. p. 115. 

 Trait^, 2de Ed. T. IV. p. 333. 



