1849.] Miscellaneous. 411 



found it to exceed the latter. Thus apparently shewing that iron alone could 

 hardly have been the cause of the attraction at * Sarraroo.' I may as well men- 

 tion that the above officer has been surveying for some years, and has had his 

 compass in use for 5 years, and never found it play such tricks before. All that 

 part of the country is famous for iron ore, and a great deal of it is smelted by 

 the natives not very far from Sarraroo, though not at that place." 



It was evident from this that at the station " 6" a deviation of some 105° was 

 occasioned by some hidden cause, and in reply to Captain Campbell, after 

 quoting to him the well known instances of deviation occasioned by basaltic 

 rocks, and that of Captain W. F. W. Owen in Canada, who found a difference 

 of 5° to 22° in bearings taken on different sides of his own house,* I suggested 

 that by digging at the spot a mass or vein of magnetic iron ore, or even a meteo- 

 rite (of which I had some hopes I confess) might be found. In his reply to me 

 in March last he states that they had dug and found at a depth of about 5 feet 

 a highly magnetic stone in large masses, occupying a space of about 10 feet 

 square, and in return for some specimens which he required from the Museum 

 of Economic Geology for the public service, he was good enough to forward me 

 a specimen of it by banghy, which is now exhibited to the meeting. Upon exami- 

 nation it proves to be simply a Dioritef with a strong admixture of magnetic iron 

 ore, giving it distinct polarity, but yet not enabling it to attract even small filings ; 

 and with numbers of minute amygdaloidal semi-crystallised grains of the me- 

 lanite variety of Garnet interspersed in its substance. Its coating is of the usual 

 ferruginous earthy kind, seen on common iron ore and basalts ; and Captain 

 Campbell informs me that the earth about it was much of this kind ; I suppose 

 a ferruginous loam or gravel. He adds that none of the basalts found in the 

 neighbourhood are magnetic, nor are there any rocks of this kind in the vicinity. 



I have carefully examined it for Nickel and Chromium, but it affords no trace 

 of them, and is thus purely and simply a highly magnetic Diorite. 



But we have here the remarkable geological fact of a considerable boulder of 

 a very remarkable rock buried in the alluvium (or diluvium) of probably a 

 distant district, and discovered by a very singular hazard ; and it may thus become 

 of high interest, when its parent rock or vein shall be found, to trace the road by 

 which it must have travelled to its present position ; for the rock is sufficiently 

 remarkable not to be passed over even as a mere geological specimen, indepen- 

 dent of its extraordinary magnetic powers, and I have thus deemed it well 

 worthy of permanent record. 



* Naut. Mag. 1840, p. 293. 



t A mineral composed of Felspar and Hornblende, 



