PITCHBLENDE PROBABLY OCCURRING IN NEW SOUTH WALES. 29 



The writer examined the radio-activity of the mineral, 

 and made as complete an analysis of it as the 4 grams 

 received in the first instance would allow. Some 10 grams 

 more were received later, but too late for full use to be 

 made of it. 



Chemical Analysis.— The original fragments of the 

 mineral were contaminated with gangue, which could be 

 readily distinguished from the pitchblende. As much as 

 possible of this impurity was removed, and the mineral 

 was then coarsely powdered and the uncontaminated grains 

 picked out. The gangue appeared to be lead sulphide. 

 The density of the most homogeneous of the original frag- 

 ments was found at 23° to be 7*3 gms. per cubic cent., and 

 of the finely powdered material analysed 7*65. The small 

 amount of the mineral received made refined and accurate 

 analysis difficult. 



The methods of analysis used are indicated in the follow- 

 ing table, they are in the main those used by Hillebrand 1 

 in his very complete study of uraninites. U0 2 was deter- 

 mined by dissolving the mineral with dilute sulphuric acid 

 in a closed tube ; solution only took place after several 

 days' heating at over 100° C. The iron present was reduced 

 by H 2 S. The uranium present as U0 2 , and iron were 

 determined by titration with N/20 KMn0 4 ; the iron was 

 also found gravimetrically, and so the U0 2 could be deduced. 

 The proportion of U0 2 to U0 3 is unusually small, I regret 

 that I was not able to verify it by a second determination. 

 The value for the content of uranium was checked. Rare 

 earths were looked for by adding oxalic acid. 



To about 2 gms. of finely powdered mineral digested on water 

 bath with 30 cc. of 2-5 E HN0 3 and then with 20 cc. 4E HN0 3 , 

 to dryness : 2-5 dilute HC1 added, evaporated to dryness, taken 

 up with dilute HC1, filtered. 



1 Bull. U.S. Geol. Surv., No. 78, 1891. 



