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clay or laterite, and secondary minerals thereby formed, gold may be among these. The gold in the case of Patawai Creek, Coromandel, must have had a different source from the gold got in Driving Creek, as its value was £3 17s. 6d. per ounce, but such deposits seem to be very small and patchy, as only £200 worth was got, I believe, by Mr. Turner, in 1862.

I would not, therefore, recommend as a guide in forming an opinion as to the prospect of gold, the mere presence or absence of paleozoic rocks, without at the same time taking into consideration their peculiar association with the pyritous rocks above referred to. The same paleozoic rocks occupy a very large area in Otago without a trace of gold, but on the West Coast of Nelson, where they are associated with pyritous felstones and porphyries, they are then auriferous.

I enclose a copy for your information, of the analysis of the rocks I refer to.

The following points deserve particular attention:—

1. Distinguish carefully the different kinds of quartz.

2. Search for the grey pyritiferous rock in the beds of the streams.

3. Areas where decomposition and siliceous infiltration has affected the rocks will be recognised by ferruginous springs and by the occurrence of large blocks of the quartz cement, which though non-auriferous in itself yet indicates the former agency of thermal springs.

4. Make a rough estimate of the area of alluvium in the district, which could possibly have been derived from the old rocks.

5. Bear in mind that no gravels of miocene age, however purely composed of quartz, have yet proved auriferous, such for instance as the quartz cements along with the brown coal formations.

(Signed) James Hector.

MEMORANDUM CONCERNING THE ROCK SPECIMENS ACCOMPANYING CAPTAIN HUTTON’S REPORT.

Thirty-eight specimens have been sent to illustrate the geology of the Karaka district, and present a similar character to the rocks from Coromandel. Among them are three specimens of auriferous quartz from Barry’s, Hunt’s, and Tookey’s claims, in two of which the gold is distinctly seen to form a large portion of the substance of the stone, the matrix being a blue splintery quartz traversed by cracks.

Respecting the specimen from Barry’s Creek, which is exceedingly rich, Captain Hutton remarks that it was broken off a specimen picked out from a sack full of stone at random.

Among the specimens sent, in addition to gold, there are samples of lead, copper, antimony; and as the samples previously sent to the Museum by His Honor the Superintendent of Auckland, contained cinnabar or mercury ore, and as the gold itself contains silver, a great variety of mineral products is thus indicated as occurring in the district.

When several of the specimens have been analysed and compared carefully with the Coromandel specimens, already submitted to analysis, the results will be communicated.

Auckland, 17th Sept., 1867.

SIR,—I have the honor to report that, in accordance with your instructions, I proceeded to the Thames gold-field on the 3rd instant. On the 4th and 5th I examined the sluicing operations in the Karaka Creek, and the various auriferous veins that had been discovered in the neighbourhood.

On the 6th I started for a tour to the northward, and examined the whole of the country at present open for prospecting, and went as far as Waipatukau Point, and returned to Shortland on the 10th instant.

On the 11th I sailed with Mr. Commissioner Mackay for Auckland, in his cutter, and arrived there at 2 a.m. on Sunday, 15th inst.

I enclose my Report on the district I visited, together with a map and section. I also send by the same steamer (Airedale) that takes this Report, a box containing specimens of rocks and minerals, and their photographs.—I have, &c.,

F. W. Hutton,
Dr. Hector, F.R.S.,
Director of the Geological Survey of New Zealand, Wellington.

REPORT OF THE GEOLOGY OF THE THAMES GOLD FIELDS.

DESCRIPTION OF COUNTRY.

The tract of country at present open to Europeans for gold prospecting in the Thames commences at the mouth of the Kauaeranga river, and runs north for about nine miles, as far as the Tuta Creek, with a breadth of about four miles: thus making the total area open about thirty-six square miles.

The whole of the country is much broken; rising, except at the mouths of four of the streams, into hills, of from 600 to 800 feet close to the sea, and increasing in height, towards the eastern boundary of the block, to more than 1000 feet. The country is for the most part covered with dense bush except where close to the sea; and the streams are all mountain torrents, with large boulders occupying their beds.

GEOLOGICAL STRUCTURE.

The geological structure of the country is very simple, being almost entirely composed of a huge mass of trachytic tuffa, resting on paleozoic rocks, which are cut by numerous dykes, mostly of diorite but occasionally of trachyte. This tuffa appears generally as a softish grey coarse-grained rock, weathering