Mr. W. J. Lewis's Crystallographic Notes. 143 





v. Bath's 

 notation. 



Calculated. 



Observed. 



001: 013 



c: \d 



51 33 



51 33 



001: 025 





56 30J 



not determined. 



001:012 



c : \d 



62 61 



62 6 



001: 023 





68 20f 



68 23 



001: Oil 



c : d 



75 10i 



75 6 



001: 312 





74 241 



74 15 



001: 311 



. c : « 



82 3i 



81 47 



001 : 310 





90 



89 55 



"312: 112 





29 32 



29 30 



.112:012 



io : \d 



25 24i 



25 27 



The plane (1 1 2) was the largest plane on the crystal, 

 (0 01) the next. All the other planes were small ; and some 

 thin twin laminae were observed intersecting the zones [0 1, 

 310] and [001, 112]. 



Binnite. — This mineral has occupied the attention of several 

 mineralogists, a summary of whose work on it is given by 

 Hessenberg in his Min. Notizen, ix., where he describes a very 

 beautiful specimen in his possession. Kenngott, after an ex- 

 amination of the crystals in Wiser's collection, came to the 

 conclusion that the mineral was hemihedral, a conclusion com- 

 bated by von Waltershausen. After a careful study of the 

 distribution of the faces on his crystal, Hessenberg comes to a 

 conclusion opposed to that of Kenngott ; for although the 

 forms {1 1 1}, {2 1 1}, {3 2 1}, {4 1 1}, and {1 0, 1, 1} were 

 incomplete, he found that the faces of {111}, {211}, and 

 {3 21} were present in an irregular manner. He has made 

 no remark, however, on the fact that the faces of {4 1 1} and 

 {10, 1, 1} are present in adjacent octants only. 



In the examination of the specimen in the British Museum, 

 especial attention was paid to the distribution of the faces of 

 the different forms. It consists of two crystals united together 

 in parallel positions, or possibly of one crystal whose free de- 

 velopment has been prevented at one point by the presence of 

 some body, and has the forms {1 1 0}, {2 1 1}, {1 0}, {1 1 1}, 

 {3 2 1}, k{4 1 1}, *{6 1 1}, k{1 1 1}, K {1 0, 1 1}, and k{2 3 3}, 

 of which k{1 1 1} is new. The forms {1 1 Of, {2 1 1} are well 

 and about equally developed ; the others are subordinate. The 

 number of octants which could be examined was six; so that 

 the question of the hemihedrism could be more thoroughly 

 tested than it was by Hessenberg, who was only able to ex- 

 amine four. The forms {110}, {211} were well developed 

 in adjacent octants, and are therefore holohedral. The forms 



