41ti Pogue and Goldsclunidt — Quartz from Alexander Co. 



T= +lf (7*6*13*7) appears with 3 well developed faces. 

 Measurement and calculations agree well. 



Measured <f>p = 27°30' ; 63°57' Calculated <f>p = 27°27' ; 63°5G' 

 27°45'; 64°08' 

 27°29'; 63°58' 



The form may he considered as established. 



?- = — |1 (1373) possesses 2 well developed faces. Meas- 

 ured and calculated values agree closely. 



Measured cpp = 25°13' ; 68°43' Calculated <^p = 25°] 7' ; 68°47' 

 24°56' ; 68°59' 



This form may also be accepted as certain. 



From an attempted discussion of the new forms according 

 to their number series,* it appeared that their relations were 

 not clear, due to the uncertainty of many published symbols. 

 The latter are often questionable, not only numerically, but 

 also in respect to their + or — character. Clearness in this 

 direction can only be attained by a critical revision of quartz, 

 following a long series of observations on good material. 



Crystal 2. (Collection of V. Goldschmidt.) Dimensions : 

 10xlS mm . Left-handed. Figs. 2a, 2b, 2c, show the crystal from 

 three sides in natural development. The distribution of the 

 faces appear in the gnomonic projection (fig. 4). The forms 

 identified are shown in the following table : 



* 



Letter b r p i h u. g 8 



Symb. Grt. pq oo +10 —10 +|0. +20 +|0 +30 —30 



— Bravais lOlO 1011 lOll 5053 2021 5052 3031 3031 



* * * 

 Letter O 0. V : f f e C p 



Symb. Gt. pq _ +^°-0 —- L°-0 +|0 +40 —40 +60 +70 —70 



— Bravais 10-0-10-3 To-0-103 7072 4041 4041 6061 7071 7071 



* * 

 Letter.. ^ s v. u. u: it- !'• x. 



Symb. Gt.pq -1L0 1 +31 —31 +-\°-l —\ s n -l +41 —51 



— Bravais ll-OMW 1121 3141 3141 10-3-13-3 io-3-133 4151 5161 



Of these forms, those designated with an asterisk are new 

 for quartz. They are well established through their measure- 

 ments, as follows : 



*See Zeitschr. Kryst., vol. xxviii, pp. 1-35, 414-451, 1897. 



