MTNERALOGICAL NOTES: No. II.— TOPAZ, BARITE, 

 ANGLESITE, CERUSSITE, and ZIRCON. 



By C. Anderson, M.A., B.Sc, Mineralogist. 



(Plates xviii. — xx.) 



TOPAZ. 



Emmaville, New South Wales. 



Since a description and figures of topaz crystals from Emma- 

 ville was published,^ Mr. D. A. Porter has presented to the 

 Trustees the specimen represented in PI. xviii., Fig. 1. It is a 

 typical and finely developed example of the crystalline habit of 

 topaz from this locality, and, as it is somewhat larger than the 

 best crystals hitherto examined, it is possible to represent the 

 faces in approximately their actual relative proportions. As 

 usual there is a comparatively rich prism zone, with the form m 

 (110) greatly predominating. Each of the prisms has four faces 

 present, but the pinacoid h (010) has only one. The three domes 

 have each the full number of faces. Of the pyramids o (221) and 

 X (243) have but three faces, while w (HI) and i (223) have 

 four. The faces are with few exceptions smooth and brilliant 

 and give excellent reflections. The crystal measures 9^ mm. x 

 5| mm. X 4 mm. The mean co-ordinate angles obtained are as 

 follows :— 



1 Anderson— Rec. Austr. Mus., v., 1904, pp. 296-299, pi. xxxix..figs. 1-3 



