’ Cox.—On the Mineralogy of New Zealand. 425 
Psilomelane, R Mn?+-H.—H. 5-6, massive and botryoidal ; colour, iron- 
black passing to dark steel grey ; streak brownish-black ; shining, opaque. 
This mineral is mentioned in the Jurors’ Rep. N.Z. Ex., 1865, p. 258, 
7 as amongst Dr. Haast’s collections. It was found in veins in the Upper 
Waimakariri. 
It is also found at the Bay of Islands, where it occurs massive and forms 
the most valuable ore; at Kawau it is found both as a massive ore and 
also as botryoidal incrustations; and at Waiheke, Waipu, and Whan- 
garei it also occurs, as well as at Ohariu, Wellington, associated with 
Manganite. It also occurs in large quantities in the island of Pakihi, 
Auckland, where it is found in numerous small veins, about 1 inch thick, 
running generally parallel to the cleavage of the slates, but sometimes at 
right-angles to it (Hutton, Trans. N.Z. Inst., vol. 1., p. 168). 
It is a valuable ore of manganese, consisting, as it does, of a mixture of 
MnO and Mn0,, but varies greatly in its composition, containing many 
: impurities. 
: 7 Awatysts or PstiomELANE FRomM Bay or IstanDs. 
Manganese oxides .. +. 75°46 
Ferric oxide .. is 11-76 
Siliceous matter 2-74 
Waiter re Fs 10°04 
—— * 
100-00 
similar composition to Psilomelane, but containing a greater quantity of 
Water, and varying more than that ore in the quantity of manganese which 
it contains. 
Analyses of these ores show that they contain from 27-14 to 87°47 per 
cent. of oxide of manganese; from 12-05 to 28-1 per cent. of water, and 
from -42 to 42-83 per cent. of silica, = ie ae 
The foregoing are the only ores of manganese which can be looked upon 
as of economic value, since their usefulness depends upon the + of 
oxygen which they contain combined with the metal; and the black oxide, 
