304 0. C. Farrington — Azurite from Arizona. 



perfect of these ; they were about 5 mm in width by 2 mm in 

 thickness. In the direction of their length, both were incom- 

 plete, the attachment at one end having prevented the devel- 

 opment of faces there. Doubly terminated crystals occur, 

 however, where the relative length is about like figs. 9 and- 10. 

 On the crystals selected the new forms Q, 223, — f and JV, 

 447, 4> were observed. The measurements given by the former 

 were very accurate and will be found in the subsequent tables. 

 These, together with its position in the zones al and c?n, suffi- 

 ciently determine its symbol. Krenner and Franzenau are 

 credited* with having observed this form on crystals from 

 Utah, but no angles are given. The form iFhas its position 

 in the zone cm and ed, but on account of its blending more or 

 less with the face 6 only approximate measurements could be 

 obtained from it in the latter zone. The best obtained were 

 as follows : 



Meas. Calc. 



N~ c, 



447 * 001, 



38° 33' 



38° 34' 



#"a X, 



44**111, 



16° 20 / 



16° 17' 



N* 0, 



447 * 101, 



27° 1' 



28° 31' 



J\ T ~ e, 



447 * 245, 



13° 29' 



12° 8' 



Figs. 9a and 10a represent the projection of figs. 9 and 10 

 upon the plane of the clinopinacoid, by which the zonal rela- 

 tions of the faces are more clearly shown. The close similarity 

 noted by Schrauf of the crystalline form of azurite to that of 

 epidote, amounting, in his view, to a kind of isomorphism, is 

 quite strikingly shown in these crystals, both in their being 

 lengthened out in the direction_of the orthodiagonal and in the 

 prominence of the pyramid o, 241, and the clinodome, p\ 021, 

 each of which correspond in angles to prominent faces in 

 epidote. While I see no reason for regarding the similarity in 

 the crystalline development of the two minerals as anything 

 more than a coincidence, the coincidence is certainly remark- 

 able. 



The faces on the free ends of these crystals were nearly all 

 very perfect, and gave sharp, well-defined reflections of the sig- 

 nal, so that the measurements obtained from them possess a 

 high degree of accuracy. The following, taken from the crystal 

 represented in fig. 9, were selected as fundamental, each meas- 

 urement having been made with great care seven times on the 

 reflecting goniometer, using the high ocular. 



O a 



241 a 241 = 65° 5 



h a h, 



221 a 22. = 105° 39' 



h~o, 



22] ^ 241 = 75° 56' 



The axial ratio deduced from these is : 



d:b:c = -85676: 1: -88603. ,3= 87° 36' 36" = 001 a 100. 

 * Zeitschr. Kryst., vol. viii, p. 53.'. 



