132 THE OCCURRENCE OF BARITE IN THE HAWKESBURY SANDSTONE. 



The purest crystals were taken for qualitative analysis j just a 

 trace of calcium was found, not a trace of strontium, no acid but 

 sulphuric, the crystals consisting almost entirely of sulphate of 

 barium. To remove any adhering ferric oxide or other accidental 

 impurity they were boiled with dilute acid before fusion. 



An exhaustive quantitative analysis would have been of little 

 value, as it was impossible to separate the crystals from the grains 

 of sand adhering to them ; but two determinations were made to 

 discover, if possible, in what proportion the sulphate of calcium 

 was present. In the first -4478 gram. S0 4 was obtained ; this if 

 combined entirely with barium would give 1*0861 gram. Ba S0 4 ; 

 the bases were dissolved and precipitated by sulphuric acid and 

 1*0876 gram, obtained; this does not allow for any calcium, and as 

 the second determination gave almost identical results, we may 

 consider, allowing for slight errors, that the pure transparent 

 crystals are Ba S0 4 , the calcium being present in very minute 

 quantities. Ba = 136*84; S = 32. ; = 16. 



It is in the conglomerate, which consists of boulders of shale 

 and ironstone cemented together with hardened sand, that the 

 barytes is found. The conglomerate overlies the upper solid rock, 

 and is also found beneath the same bed, a distance of 10 or 12 

 feet separating the two. Shale is found embedded in the solid 

 rock, but the barytes does not appear to exist there, although it is 

 found both in the upper and lower conglomerates. 



The shale contains much mica. 



I have not succeeded in obtaining the barytes in any large 

 quantity, the conglomerate not being of large extent, although 

 there is no reason to suppose that it is restricted to that deposit, 

 and perhaps now that its presence in the immediate neighbourhood 

 of Sydney has been ascertained, larger quantities may be found. 



In the many crystals examined no new faces were seen, there- 

 fore further description is not required. 



The best specimens have been placed in the Technological 

 Museum Collection. 



