56 COLORADO FERBERITE AND THE WOLFRAMITE SERIES. 



The forms fit well into the normal series notwithstanding their 

 complex indices. 



(3) Zone segment d ...... a. 



Form ( d G M N ~ f L n a 



- ' 1310 720 510 11. 2. 610 710 810 100 



Symbol=| ..................... 3-5 ~ 6 7 8 



v-3 ............................ 2 345oo 



v-2 ............................ 



\\ \ 



All the new prisms fit well into the normal series. 



Five very distinct habits were observed on the crystals examined, 

 habit meaning the relative development and size of the different 

 crystal faces and the consequent resultant shape of the crystal as 

 a whole. Thus twin crystals are not considered as necessarily of 

 different habit from a simple untwinned crystal. These fire habits 

 are as follows: 



1. Long, narrow, wedge-shaped. This is the habit most frequently 

 observed for the ferberite crystals studied. This is the habit of the 

 penetration twins (figs. 17 and 18, p. 64) but not of the contact twins. 

 (See Pis. VII and VIII, A, pp. 18, 19, and fig. 3.) 



2. Short, prismatic, somewhat flattened parallel to the ortho- 

 pinacoid {100}. Crystals of this habit are fairly abundant. (See 

 Pis. IX, p. 20, and X, p. 21, and fig. 4.) 



3. Tabular, parallel to a{100}. Rarely observed in simple crystals 

 but the common habit for the individuals of a contact twin. (See 

 fig. 5, also the twin crystals shown in figs. 14 and 15, p. 63.) 



i Tfii (See PI- VIII, B, p. 19, and fig. 6.) 



5-^Rhombic, fairly abundant. (See Pis. XI, p. 22, and XII, p. 23, 

 and fig. 7.) 



Besides the habits mentioned above, two forms were noted which 

 owe their shape to the cleavage of the crystals and are therefore not 

 habits of the mineral. The first of these forms occurs in thin plates, 

 which, as can be seen by reference to figure 8, A (p. 58), owe their 

 tabular appearance to the 6(010} cleavage. The complete crystal 

 from which this thin plate was cleaved was probably of the fourth or 

 cubic habit. The second form occurs in long, slender rods and like- 

 wise owes its peculiarity of form to cleavage. As illustrated in figure 

 8, B, it is probably derived from the edge of a crystal of habit 1 (see 

 figs. 3 and 9), where the prism Z{210} extended to the edge of the 

 crystal. 



