452

LEAD,

white, and sometimes much stained with peroxide of iron. Where cut by dykes, it is hardened for considerable distances, and much altered in appearance. As might be expected, however, from its origin, it varies a good deal in character: often containing rounded blocks of diorite one or two feet in diameter; indeed, in three or four places it passes into a true conglomerate, while occasionally small angular stones are seen in it, forming a breccia. The latter, however, are very local.

Near Hengikori the rounded blocks of diorite are encased with a coating of red jasper.

The rock is also traversed by numerous veins of quartz, carbonate of lime, or both these minerals mixed together, in which case it is seen that the carbonate of lime is a subsequent introduction, as it is found encrusting well-formed crystals of quartz.

The whole of the rock, including some of the dykes, is much impregnated with iron pyrites generally in the form of minute cubes, but decomposed to a grey powder near the auriferous veins.

GOLD VEINS.

Auriferous quartz veins had been found in eight different localities on the 11th September. The gold is similar in character to that found at Coromandel.

HUNT’S REEF.

Hunt’s “Reef” as it is called, is a mass of trachytic tufa over which the water of the Kuranui Creek falls. The face thus exposed is traversed by four small, nearly vertical, veins of quartz with gold running N. by E.

BARRY’S REEF.

Barry’s “Reef” about 100 yards higher up the creek, is a vein of mullock about a foot thick, dipping 70 degrees W. The gold occurs generally in more or less rounded nodules (like flints in chalk) of quartz, some of which are very rich. This vein is exposed on the right bank of the creek for a distance of about 15 feet.

TOOKEY’S REEF.

Tookey’s “Reef” consists of a series of small veins of auriferous quartz dipping 50 degrees N.W. It is situated about 220 feet above the level of the sea, on the side of a hill of trachytic tufa, between the Kuranui and Moanatauri Creeks.

COPPER.

A little north of Waiuau a lode of copper occurs, below high water mark, running N.N.E. into the hills, where, however, owing to the vegetation it cannot now be seen. The ore appears to be a mixture of iron and copper pyrites, like that at Kawau, with some red oxide. The specimens sent have been lying on the beach for some time. This lode also occurs in the tufa. Small specks of copper pyrites often occur together with iron pyrites in the quartz veins traversing the tufa.

LEAN.

About 2½ miles up the Tararu Creek, in the tufa, hardened by its proximity to a dyke of diorite, a quartz vein occurs with crystals of galena, dipping 70 degrees N.N.E., and in one of the claims now being worked in the Waitohi Creek, crystals more than an inch long, of stibnite, (sulphide of antimony), has been found imbedded in the tufa.

AGE OF TUFA.

This tufa is probably of tertiary age, and not older than the Waitemata veins.

STRUCTURE.

There are no marks of bedding nor stratification to be seen, but from the extent of country that it covers, and the general vertical direction of the dykes, I think that it is not far from horizontal, dipping probably slightly to the west or north-west. The absence of slate boulders in the streams and on the coast, seems to show that this tufa extends over much more ground than that visited by me, and I can see no reason why auriferous veins should not be found in any part of it. These veins, being thin and variable, must always render gold mining in this district highly speculative, and if, as I believe, the stratification is nearly horizontal, deep sinking will be useless, and in order to enable a company to make a profit, it will require more ground than that usually allotted to a gold claim.

PALEOZOIC FORMATIONS.

In one locality only, between the Tararu and the Waiohanga Creeks, are paleozoic rocks seen in the district. They here consist of blue arenaceous slates covered by a fine grained felsite tufa, the whole dipping 35 degrees S.W.

TERTIARY TRACHYTIC TUFA.

Lying on the tops of the old tufaceous hills, between Shortland and Tararu, a deposit of fine red and white trachytic tufa is seen of a much later date than the old one on which it rests. This does not cover much extent of country, and is probably of pleistocene age, and formed by the former eruptions of Aroka mountain.

ALLUVIUM.

The largest quantity of alluvium in the district is that between the Kauaeranga and Kuranui streams. This I estimate to cover an area of 700 acres, out of which 100 acres must be deducted for the township of Shortland, and 200 more for tapu burial grounds, leaving 400 available for diggers. This tract may be considered as an incine sloping up from the sea to a height of 40 feet at the foot of the hills. It is an old sea beach covered, where the creeks debouch into it by recent fluviatile accumulations.

SLUICING.

These latter, at the Karaka, have been worked by sluicing pretty systematically for the last three weeks, and the results have