IRON. 



385 



Fig. 443. 



Fis. 441. 



at tliis locality. According to Dr. Horton, 

 the cube with the edges truncated, Fig. 443, 

 has also been found here. 



Octahedrons of the same species also oc- 

 cur at Amity in this county, and a few dode- 

 cahedrons have been observed at a localily 

 six miles south of Warwick. Fig. 444. 



The specimens from the Rich iron mine 

 arc remarkable for the ease with which they 

 cleave in the direction of the primary octa- 

 hedron. This cleavage is exhibited, though in a much less distinct manner, in specimens 

 from several of our other locahties. 



SPECULAR IRON ORE. 



[From the Latin sjieaihim, a mirror ; on account of its brilliancy.] 



Per Oligistc. irmii/. — Specular Oxide of Iron. Cknirl/iiul. — Specular Iron Ore. Thomson. — Specular Iron. 

 Phillips, Da 11,1 anil Sfirjinrd. — OUgiste. Bcudunt. — Rhombolietlral Iron Ore. J,iin':son. — Rhomboedriaches 

 Eisen-Erz. MhIis. 



Fig- 445. Descrii^tion. Colour dark steel-grey bordering on iron- 



black, iron-black and brownish red. Streak red or reddish 

 brown. It occurs regularly crystallized ; and also massive, 

 disseminated, reniform, botryoidal, stalactitic and globular. 

 Primary form a rhombohedron. Fig. 445. P on P S6° 10', and 

 93° 50'. Fracture conchoidal or earthy. Lustre metallic or 

 semi-metallic. From transparent to opaque. Hardness from 

 5.5 to 6.5. Specific gravity from 4.80 to 5 . 30. Sometimes 

 feebly magnetic. Infusible by the blowpipe alone ; with borax, 

 it melts into a green or-yellow glass, like the magnetic oxide. 

 It is usually soluble in hot muriatic acid. 

 The red powder of this mineral, and its feeble action on the needle, will in general be suf- 

 ficient to distinguish it from the preceding species. 



Varieties. The most strongly characterized varieties are the Specular Iron Ore, or Iron 

 (rlancc, which includes those which have a black colour and arc more or less regularly crys- 

 tallized ; the Red Iron Ore and the Red Hematite, which have a red colour, the latter being 

 fibrous. 



Composition. When pure, the specular iron ore is a pure peroxide of iron, containing 

 69.34 of iron, and 30.66 of oxygen. ]5ut it ahuosl always contains foreign matters, either 

 earthy or saline. Formula Fc:0> 



MiN. — Part II. 49 



