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Art. XLIV. — On a Carbonaceous Mineral from Whangarei Harbour. 

 By Captain F. W. Hutton, F.G.S. 

 [Bead tefore the Auchland Institute, September \2, 1870.] 

 At One-tree Point, on the western side of Whangarei Harbour, a carbonaceous 

 mineral, resembling coal in appearance, occurs under such curious circum- 

 stances that I think a short notice of it will prove interesting. 



One-ti-ee Point consists of low cliffs, some twenty feet high, of soft 

 horizontal quaternary sandstones, witli casts of marine shells [Pecten, etc.) 

 The upper stratum is yellowish sand, the middle one more ferruginous, while 

 the lower one is blackish or brown, from the quantity of carbonaceous matter 

 scattered through it. On the face of the cliffs, several irregular oblique 

 fissures, from one to six inches in breadth, are seen traversing all the beds. 

 These fissures are generally filled uj) with sand, but some of them, when they 

 enter the dark coloured lower stratum, are filled with carbonaceous matter, 

 which is much mixed with impurities near the sides of the vein, but in the 

 centre is nearly pure. Sometimes the centre of the vein is empty, with the 

 pure carbonaceous mineral lining both sides. These fissures are similar to 

 ordinary veins, and do not bear any resemblance to holes made by roots of 

 trees, etc. 



The mineral from the centre of the vein has very miich the appearance of 

 cannel coal. Its colour is black, with a shining resinous lustre. Streak and 

 powder black. Very brittle, but does not dirty the fingers. Hardness 

 about 2. In the fiame of a spirit lamp it burns to a white ash without 

 altering its shape, and without giving off any odoiir or smoke, but it will not 

 burn if taken out of the fiame. It appears to be nearly pure carbon, without 

 any admixture of bitumen. 



These phenomena appear to me to be inexplicable, except by supposing 

 that the carbon has passed in a state of solution from the sandstone into the 

 fissures, and that it has then been deposited on the sides of the veins. If the 

 process had been one of sublimation, the mineral would also be found at a 

 higher level than the upper surface of the dark coloured sandstone, which is 

 not the case. And if both it and the carbonaceous matter that colours the 

 sandstone had been sublimed from below, and impregnated both the vein and 

 the rock, it is evident that the vapour would have ascended further up the 

 fissure than through the rock. "What, however, the solvent could have been 

 I cannot even conjecture. Specimens of this mineral were forwarded to the 

 Colonial Museum by me, in 1866. See Colonial Museum and Laboratory 

 Reports, 1866-67, page 17. 



[The following is the composition of the carbonaceous mineral, which 

 appears to be a non-caking lignite approaching jet, burning with difiiculty, giving 

 but little flame and a white ash : — 



