ORDER VIII. RHOMBOHEDKAL IRON-ORE. 405 



2. R 2. R. Elba. 



3. R oo. P -f- 1 . Framont, Lorraine. 



4. R -x. R. P + 1. Sim. Fig. 143. Alten- 

 berg, Saxony. 



5. R 2. R. P + 1. Fig. 124. Elba. 



6. R 3. R 2. R 1. R. (P 2) 5 . P+l. 

 R + 1. i p + 3. Elba. 



Cleavage, R QD. R. In some varieties scarce 

 any traces appear, while in others it seems to be 

 perfect, which, however, must be in a great mea- 

 sure attributed to composition. Fracture con- 

 choidal, uneven. Surface, those rhombohedrons 

 which are in parallel position with R, as R 4 9 

 R 2, R -f oo, particularly the obtuse ones, are 

 horizontally streaked, sometimes so deeply that 

 they appear rounded ; R is sometimes streaked 

 parallel to the edges of combination with P -f- 1 ; 

 R 3 is uneven and often curved, it is striated 

 at the same time parallel to the edges of combi- 

 nation with R 2 ; R 1 is sometimes curved 

 but always smooth. 



Lustre metallic. Colour dark steel-grey, iron-black. 

 Streak cherry-red, reddish-brown. Surface fre- 

 quently tarnished ; generally with the exception 

 of R oo, which may be useful to beginners in 

 finding the true position of the crystals. Opake; 

 very thin laminae are faintly translucent, and 

 shew a deep blood-red colour. 



Brittle. Sometimes feeble action upon the magne 



