﻿S. L. Penfield — Crystallized Vanadinite. 



443 



and quite closely with that of Vrba,* 1:0*7112177. The 

 measured angles are as follows : 









Measured. 



, uaicu 



Yrba. 



iaiea. N 



Author. 



a 



a v 1120 



/^ 



1122 = 54° 



30' 



54° 



33' 



54° 



35' 



m 



a r 1010 



A 



1012 = 61° 



42' 



61° 



39' 



61° 



41' 



m 



^ x 1010 



A 



1011 = 50° 



33' 



50° 



34' 



50° 



36' 



m 



a y 1010 



A 



2021 = 31° 



20' 



31° 



18' 



31° 



20' 



X 



a x 1011 



A 



0111 - 31° 



2' 



37° 



2' 



37° 



0' 



X 



^ 5 1011 



^ 



1121 = 26° 



36' 



26° 



38' 



26° 



36' 



s 



^ M 1121 



A 



2131 = 14° 



0' 



14° 



2' 



14° 



1' 



m 



^ w 1010 



A 



2131 =30° 



55' 



30 c 



50' 



30° 



52' 



c 



a % 0001 



A 



2131 = 65° 



11' 



65° 



19' 



65° 



11' 



m 



a h 1010 



^ 



2130 = 19° 



9' 



19° 



6' 



19° 



6' 



It will be seen that the angles agree closely with those calcu- 

 lated from the axial ratio of Yrba, also closely with those of 

 the author. 



The crystals contain only a trace of As 2 5 , which was 

 proved by testing in the Marsh apparatus. 



I have also examined crystals from the Sierra Grand Mine, 

 Lake Valley, Grant Co., New Mexico. These are straw yellow 

 in color and have the habit shown in fig. 4, many 

 of them have a more prominent basal plane. 

 The prism m is usually striated horizontally. 

 The crystals react strongly for V 2 5 and in the 

 Marsh apparatus for As 2 5 , corresponding ex- 

 actly to the description given by F. A. Genth 

 and G. vom Eathf to the species named by them 

 Endlichite (vanadium mimetite). The observed 

 forms are given in fig. 4, z == 3031, 3. The crys- 

 tals do not admit of very accurate measurement. 

 From the best measurement x^x' (ion a0iIi)=38° 12' we ob- 

 tain the ratio a : c = 1 : 0*7495, Other measured angles are : 



x a as"' 1011 ~ 1011 = 82° 3' 



y a y' 2021 a 0221 = 51° 51' 



x a y 1011 n 2021 = 18° 25' 



x a z 1011 a 3031 = 21° 44' 



Endlichite. 



Yanadinite, Author. 



81° 45' 



18° 41' 



51° 18' 



50° 34' 



19° V 



19° 16' 



28° 3' 



28° 31' 



It will be seen from the above that the angles do not agree 

 well with the calculated angles of vanadinite. The presence of 

 As 2 s in the mineral must therefore tend to very perceptibly 

 increase the length of the vertical axis. 



Mineralogical Laboratory, Sheffield Scientific School, June 16, 1886. 



* Loc. cit. 



f Proc. Amer. Phil. Society, xxii, 361. 



