34 Penfield and Frenzel — Identity of Chalcostibite, etc. 



In addition to the perfect basal cleavage, traces of cleavages 

 parallel to the pinacoids 100 and 010 were observed. 



In the succeeding tables, the calculated values are derived 

 from the axial ratio a\b\G — 0*5312 : 1 : 063955, and the meas- 

 urements made by various investigators are indicated by 

 Roman numerals placed above the columns, as follows : 



I. Laspeyres. Crystals from Wolfsberg in the Harz. 

 II. Friedel. Crystals from Guejar in Andalusia. 



III. Penfield. Fragment of crystal from Guejar, received from 



Prof. Friedel. 



IV. Penfield. Fragment of crystal from Guejar, received from 



Prof. Groth. 

 V. Schott. Terminated crystal from Guejar, belonging to the 



Munich collection. 

 VI. Penfield. Crystals from Huanchaca, Bolivia. 

 VII. Spencer. Crystals from Huanchaca, Bolivia. 



Measurements from the base c, 001 on to faces in the zone 001 : 100. 



Calculated. I. II. III. IV. Y. TI. 



c A A, 209 14° 59' 14° 10' 



CaA,, 207 18 59 17 40 



c A A a , 303 21 52 21° 55' 22° 21' 



c A A 3 , 205 25 43 25 55 



c^e, 307 27 m 27° 12' 27 11 



c*j, 102 31 3 

 c A h, 203 38 45 

 G/^d, 101 50 ]7 51 22 

 C/\ i", 302 61 l£ 

 c^g, 201 67 27 66 28 



To the foregoing may be added the measurements of Rose 

 A d=5O o 3O' and ca£ = 67°36', and the following by 

 Spencer: caA, = 25°49' (mean of 25° 51', 25° 55', 25° 51' 

 and 25° 35') and c A *=63°, 63° and 63° 13'. These last 

 measurements by Spencer and one given by Friedel, c<\i = 

 62° 50', may indicate the existence of a form 805 (001 a 805 = 

 62° 34/) instead of the more probable one i, 302.. 



Measurements obtained from faces in the zones 100 : 010 and 



010 : 001. 



II. Y. VI. 



64° 22' 



31 



3 











39° 58' 38 



45 



38 



46 



38°51' 37 





50 34^ 50 



32 



50 



25 



50 18 50 



42 



62 50 









61 



45 



67 39 67 



8 



67 



22 



67 24 67 



24 





Calculated. 



I. 



I ss I, 130 A 180 



64° 13' 





c A /, 001/vOll 



32 36 



32° 21' 



f^f\ 011 A 011 



114 48 



116 31 



« A «, 065 A 065 



104 59| 





C A £, 001/^021 



51 59 





tss t, 021 A 02l 



76 2 





c a m, 001 A 061 



75 23| 





u^u, 061 A 061 



29 13 





51° 54' 



75 23 75° 24' 



105 24 

 76 21 

 29 32 



