S£8 Transactions. — Geology. 



but simply a lichen-like arrangement of the branches. These 

 are always argentiferous in a high degi'ee, and their colour 

 varies from light-yellow to pure silver-white. Figs. 48-50 show 

 the three principal arborescent varieties. 



Coarse, angular, often partly-crystallized specimens of gold 

 occur principally in small pockets along the road leading from 

 Owharoa to Waihi and Waitekauri. This gold is remarkably 

 free of silver, compared with that obtained in the mines at 

 Owharoa. The sharp edges prove clearly that it was not car- 

 ried a long distance ; but tunnels driven in the hill-side led to 

 no satisfactory result. It is to be hoped that further prospect- 

 ing will be done in this very promising locality. 



Granular gold is the most common in Ohinemuri. The 

 best prospects were washed out from soft debris near the 

 Hauraki camp, Karangahake, which showed all the different 

 modifications. Figs. 1 and 2 illustrate typical specimens. 

 They are probably derived from a highly ferruginous rock, 

 not unlike that successfully worked in the Woodstock Mine. 

 The particles are often very minute, globula,r or elongated, but 

 with roimded ends, often filamentous in the form of a rosary, 

 or botryoidal, &c. These forms appear to be limited in their 

 distributiou to veins rich in iron-oi'e, and the so-called "blue 

 veins," which, when oxidized, disclose the gold often to the 

 naked eye. Extremely small almost spherical particles are 

 present in almost all the blue veins, especially those contain- 

 ing a fair percentage of silver. Treatment with acids shows 

 that the gold is present in a very fine state, though when ex- 

 posed to oxidizing agencies comparatively large agglomerations 

 of grains are seen. It is likely that the gold exists in most 

 pyrites in molecular form, and that during the process of decom- 

 position the molecules join, forming these tubercular aggregates. 

 Figs. 32-35 show the gi-ains of gold in decomposing pyrites. 

 When the oxidation is not sufficiently far advanced to render 

 the mineral friable, the gold necessarily does not come iu con- 

 tact with the mercury in the battery. In the tailings frag- 

 ments of an ochreous colour containing gold are often found, 

 which accounts for the great discrepancy between the assayed 

 and crushing value of the ore. Roasting and the chemical 

 processes lately tried on the Thames and Ohinemuri Goldfields 

 will eventually save the greatest part of this gold. 



Enormous quantities of iron-pyrites, which we may sup- 

 pose were auriferous, have entirely disappeared, leaving but 

 the walls of quartz. It is clear that the gold they contained 

 was deposited in other places. Borings at the lower levels 

 will no doubt lead to its discovery in very rich veins. 



Larger masses of gold, irregular in shape but with a smooth 

 surface, similar to alluvial nuggets, are found occasionally. A 

 spociinen about 4 millimetres in length was washed out of a 



