131 



PAPERS KKAI). 



ON THE OCCURRENCE OF BARITE (BARYTES) IN 

 THE BAWKESBURY SANDSTONE NEAR SYDNEY. 



Ky ii i:mcv (i. Smith, Laboratory Assistant, Technological 



Muskum, Syonky. 



(Com/nvunioaited by ■/. II. Maiden^ F.L.S., &c. t Curator 

 <>f the Museum,) 



Uninteresting ; >« the Hawkesbury sandstone around Sydney is 

 generally considered to be, especially from ;i collector's point of 

 view, and although the inducement to search for either metallic 

 or Hon metallic minerals is not great, yet sometimes one Is 

 rewarded for a diligent search among the cracks and crannii 

 old or recent excavations. 



In a quarry not far from Cook's River, five miles west from 



Sydney, and adjoining the Tllawarra road in the borough of 

 Marrickville, I recently found Barytes in very perfect and pure 

 crystals. They have a vitreous lustre, which on the most perfect 

 crystals is very brilliant; it was their sparkling, in the sun that 

 first drew my attention to them. They are in many instances as 



transparent as glass, and crystallise for the most part in modified 

 tables of the; right rectangular pyramid, the domes being cut off 



by the basal pinakoids. In many crystals the faces of the right 

 rhombic prism are, distinct ; the symbols for the majority of the 

 most perfect crystals are, therefore : — co P + P Go + P cx> + OP. 

 The pinakoids OoPoo and a,Pa> being occasionally, although 

 seldom, developed. The faces of the right rhombic prism are 

 extended upon the macro-diagonal axi«, and in a few larger- 

 crystals the extension has continued to the almost extinction of 

 tin; macro-domes. 



The purest and best formed crystals are of small size, but some 

 measure J inch on the macro-diagonal, though these larger crystals 

 are not so pure nor so transparent ; their thickness is j\. inch. 



