MINKKALOOIOAL NOTES : NO. V. — ANDERSON. 



405 



Elsmore, New South Wales. 



(Plate Ixxv.. figs. 2, 3). 



Fine crystals of tinstone are found at Elsmore, where they 

 occur disseminated through greisen ; weathering sets free the 

 cr3\stals which become concentrated into alluvial deposits of 

 economic importance. A large proportion of the crystals are 

 reddish, forming the so called ruby tin. The usual habit is stout 

 prismatic, and the crystals seem to be invariably twinned on « 

 (101), the usual law; doublets are comparatively rare and some 

 of the crystals are very complex. Fivelings in wliich a large in- 

 dividual supports on each e face a smaller crystal in twin position 

 are abundant, and specimens showing the nine individuals com- 

 posing a complete twin crystal of this type are b}'^ no means un- 

 common. 



In PI. Ixxv., fig. 2, is represented according to its actual 

 development a doublet of -75 x "5 cm. in which the two 

 portions are about equal in size and development and the line 

 of junction is barely visible. Unfortunately this beautiful crystal 

 is fractured on one side where it was attached to the matrix. It 

 is essentially similar to the crystal figured by Becke,^ which how^- 

 ever has no z planes. The forms determined and the mean co- 

 ordinate angles are tabulated below : 



Bec-ke -Mill. Mittli., Heft 3, 1877, pi. i., f. 5. 



