356 Transactions. — Chemistry. 



and unless great care was taken, and skilled workmen em- 

 ployed, a great deal of this material found its way into the 

 parcel. 



As this ore is always purchased upon its assay-value, and 

 every effort is made to obtain a true average sample of the bulk, 

 it will be seen how necessary it was to have the ore as free as 

 possible from foreign material ; and, owing to the soft, black, 

 unctuous portions of the ore staining the accompanying worth- 

 less material, it was not always possible to do more than free 

 it from a portion of the gangue. 



The deposits of manganese ore hitherto worked have been 

 located solely in the manganiferous slates, where they occur, as 

 already mentioned, in irregular patches or bunches, sometimes 

 having for a distance the appearance of a true lode, but seldom 

 for any extent, the irregularity of its borders breaking off with- 

 out continuance, though occasionally some more extended off- 

 set would be carried to another bunch. This peculiarity of 

 the ore has made the mining of it a matter of great difficulty 

 and anxiety. 



As I have already mentioned, the mines hitherto worked 

 have been solely in the slates ; but this ore occurs in many 

 other parts of the district than those already mentioned, 

 notably at Kawau, where specimens of very fine ore 

 have been obtained ; again, at the island of Pakihi it 

 has been mentioned as occurring in large quantities, by 

 Professor Hutton.''' I have also found it in the Mareatia 

 district, vv'here I have no doubt it will be found in suffi- 

 cient quantities and richness to make it of commercial value. 

 It is also known to be present in the hills to the west 

 of Waipu, where it may be seen outcropping on the track 

 between that village and the caves. Still further north it is 

 found in larger and smaller quantities between Whangarei and 

 the Bay of Islands, and, again, in the vicinity of Mongonui. 

 There is no doubt that large deposits of this ore will be yet 

 discovered when it becomes of sufficient value to warrant 

 extensive prospecting. 



The manganese shipped from this port is chiefly psilomelane, 

 though some very fine specimens of pyrolusite have been 

 obtained from Whangarei. From this part of the distinct — 

 Parua Bay — some samples containing very high percentages 

 of peroxide have been lately shipped. 



The necessity of shipping nothing but high-grade ore is on 

 account of the home market requiring nothing below 70 per 

 cent, of peroxide when purchased for bleaching purposes, as 

 the consumption of hydrochloric acid for the manufacture of 

 chlorine is less the higher the percentage of peroxide present 



* "Trans. N.Z. Inst.," vol. i., p. 168. 



