E. JS. Dana — Chondrodite from the Tilly-Foster Iron Mine. 91 



Very little further can be said in regard to the crystals of tlie 3d 

 type. Those observed had a somewhat diiferent color from those of 

 type II ; that is, the color was more yellowish, less of a pure garnet- 

 led — though this may be accidental. No analysis was possible of 

 coui'se; and even the sjjecitic gravity was out of the question also, for 

 the one loose crystal, in addition to its small size, had imbedded in 

 it a still smaller crystal of ripidolitc, making any gravity determina- 

 tions obviously uurelial)Ie. 



The method of occurrence was much like that of the brilliant crys- 

 tals of the second type ; that is, they w^ere found implanted on the 

 massive rock adjoining small veins. The associated minerals Avere 

 magnetite, ripidolite in clear transparent crystals, and, probably as a 

 later formation, brucite. 



3. Description of Crystals of Type I. 

 The occurrence of large, coarse crystals of quite impure chon- 

 drodite, imbedded in the massive material, has already been de- 

 scribed ; these belong, at least in part, to the first of Scacchi's 

 types. As has been remarked, the crystals of this character do 

 not often admit of exact determination, but in two cases they 

 were so good as to allow of their crystallographic relations being 

 accurately made out. The accompanying wood-cuts, figui'es 22 

 and 23, give faithful representations of their appearance and size. 



RU 



R^ 



R^" 



Fig. 22. Fig. 23. 



It will be seen that they are both quite imperfect, and it was on this 

 account that no attempt was made to make a symmetrical drawing 

 of either of them. In each case the crystals w^ere so distorted as to 

 give a sharp edge between the diagonally situated pyramidal planes; 

 this furnished an opportunity for relial)le measurements. The plant's 



