ORDEE Tin. , OCTAHEDRAL IRON-OBE. 399 



OBSERVATION'S. 



1. The chemical composition of axotomous Iron-ore has 

 not been exactly ascertained. It is likely to consist of the 

 oxides of iron and titanium. 



2. It occurs in imbedded crystals and grains in several 

 varieties of prismatic Talc-mica, and macrotypous Lime- 

 haloide, in the valley of Gastein in Salzburg, and frequent- 

 ly along with the crystals of peritomous Titanium-ore, over 

 which it often forms a black coating, as at Klattau in Bo- 

 hemia, in the gold stream-works at Ohlapian in Transylva- 

 nia, &c. 



3. The mineral most nearly resembling axotomous Iron- 

 ore, if we compare the descriptions published, is the Crich- 

 toniie of Count BouRNOir (Fer oxidnle tltani. HAUY. 

 Traite', 2de Ed. T. IV. p. 98), at least, as to the general 

 nature of its forms, and the other properties, which, how- 

 ever, are not ascertained in the Crichtonite with sufficient 

 accuracy. According to Count BOURNON, the primitive 

 form of this substance is an acute rhombohedron, whose 

 plane angle at the apex is = 18. The Abbe' HAUY from 

 this observation deduces the ratio of the diagonals = */ 40 

 : 1, from which the axis follows = x /267'75, and the ter- 

 minal edge = 60 50'. Its most common crystalline forms 

 are combinations of this rhombohedron with II os, similar 

 to Fig. 113., or also flat twelve-sided prisms, which have 

 never been accurately described. Its only locality is the 

 department of the Isere in France, where it occurs in nar- 

 row veins along with pyramidal Titanium-ore. It consists, 

 according to BERZELIUS, of oxide of iron and oxide of ti- 

 tanium. 



2. OCTAHEDRAL IRON-OttE. 



Octahedral Iron-Ore. JAM. Syst. Vol. III. p. 188. Man. 

 p. 244. Oxydulated Iron. PHILL. p. 221. Magnet- 

 eisenstein. WERV. Hoffm. H. B. III. 2. S. 216. Mag- 

 neteisenstein. HAUSM. I. S. 245. Magneteisensteio- 



