126 



KECORDS OF THK AUSTRALIAN MUSEUM. 



QUARTZ 



MooNBi, New South Wales. 



(Plate xxxvii., fig. 6.) 



Mr. D. A. Porter informs me that this fine example of a quartz 

 crystal twinned on the Japan law (twinning plane ^ (1122)) was 

 found with several similar twins in situ at a depth of ten or 

 fifteen feet about two and a half miles S.S.E. from Moonbi 

 Railway Station. It has the usual flattened form of the Japan 

 twin and the two segments are united in an irregular line ; 

 height 2 cm. For measurement each segment in turn was 

 mounted in the conventional position to furnish the meridian and 

 polar plane to which the poles of both segments were referred. 



ANGLES. 



Forms. 



m 

 r 



z 



8 



m 



Measured. 



Calculated. 



11/ 



1010 

 1011 

 01 

 1121 



iqlo 



lOll 



01 Fi 



29 59 



9 15 



5 34 



21 55 



89 59 



51 49 



65 44 



30 24 



42 40 



86 39 



90 

 51 47 

 33 



(jo 



30 27 



42 36 



86 38 



Difference. 





 



1 



s 



5 

 20 



11 

 3 

 4 

 1 



NuNDLE, New South Wales. 



(Plate xxxvii., fig. 7.) 



This Japan twin differs somewhat from the preceding. One 

 segment is much larger than the other and above the junction (as 

 fiaured) the larger segment tapers rapidly, while below it is of less 

 dTameter ; height 2-7 cm. The apex of the smaller segment can 

 be traced within the other but not distinctly. The twin is very 

 similar to that from Dauphine, described by Goldschmidt*. 



eOoldschmidt— Zeits. Krynt., xliv., 1908, p. 415, pi, ix., figs. 2. 3. 



