W. IT. Melville — Metacinnabarite from California. 293 



Analogue Pole. 



Miller. Bravais-Miller. 

 (h k I to) 



Basal plane k(111) k(0001)' 



Positive hemi-rhornbohedron /c(100) k(1101) 



Negative rhombohedron re(332) /c(0554) 



Hemi-scalenohedron.. k(2U) k(1322) 



Antilogue Pole. 



Negative hemi-rhorobohedron k(33,.17, 17,) k(50, - 50, 0, I) 



Hemi-scalenohedron k(31, 17, 15) /c(48, 46, 2, 1) 



Hemi-scalenohedron /c(26. 15, 12 ) /c(41. 38, 3, 1) 



Angle of axes (Miller)=118° 11' 20" 



Axial ratio c: a = - 2372 : 1 (Naumann). 



: co a: co a: 

 : a: a: x a 

 c: oo : 1 : 1 

 1:1 



ic 



50c: 

 48c: 

 41c: 



1 : 1 : oo 

 1 : U : 24 



1 . ii . Ai 







Measitrements 













Measured. 



Calculated: 





Ill ^ 100 



— 



15° 



19' 







100^010 





26 



29 







100^211 





4 



15 







111 ~33, 17, 



IX 



94 



10 



94° 10' 36 





111 ^31, 17, 



15 



94 



31 



94 33 





111 ^26, 15, 



12 



94 



42 



95 17 



33, 



17, 17^17, 33, 



17 



119 



28 



119 28 



33, 



17, 17 ^ 31, 17, 



15 



2 



6 





33. 



17, 17^26, 15, 



12 



3 



55 





Fig. 1. 



Fig. 2. 



The poles of the scalenohe- 

 drons in the negative hemi- 

 sphere almost belong in the zone 

 circles passing through any two 

 poles of the negative rhombo- 

 hedron, therefore, as shown in 

 the figures the planes of the for- 

 mer do not exactly bevel the 

 terminal edges of the latter. 

 The f a c_e s of the former 

 *(26, 15, 12) are tectonic and con- 

 tain series of re-entering angles 

 (fig. 2) which indicate the build- 

 ing up of that portion of the 

 .crystal rather than twinning. 

 Otherwise striations are absent, and owing to the brilliancy of 

 the plane surfaces sharp reflections of the signals on the goni- 

 ometer were obtained. Fig. 2 was drawn with the aid of . 

 cross-hair and graduated stage _of the microscope and in such 

 position that the face (83, 17, IT) is parallel to the plane of pro- 

 jection. The following plane angles were read: a=86° 20', 

 £=82°45, r =39, o = 85° 30', ^=24°. The relations of these 

 angles with the elements of the crystal have not been made 

 out. With the exception of x(332) all the observed forms are 



