CAPT. HUTTON'S REPORT ON ITHE KAKAKA GOLDFIELD.

Wellington Independent, Volume XXII, Issue 2591, 31 October 1867, Page 4

CAPT. HUTTON 'S REPORT ON ITHE KAKAKA GOLDFIELD.

September 23, 1807. Sir, — I have the honor to forward, for tho information of the Hon. the Colonial Secretiiry, tho ri'poft of Captain Hutton on tho Karaka. goldfield in the Thames district of Uio province of Auckland, obtained iti accordance with Uio authority conveyed in your letter of 2Stli August last, No. 67-2796. This report, I consider, proves satisfactorily the existence, iu the district referred to, of gold-bearing formations similar iu their nature to those at, Ooromandel ; and that, in forming an estimate of the extent to winch (hey are capable of development, the experience of Ihe diggings at that place should be taken as a guide. The appended extract from my instructions to Captain Hul ton expresses myewn views on tho structure of the adjoining district, founded on observations made in 18G4 and 1866. The association, of gold with volcanic rocks belonging to the tertiary period, near the point where they have been erupted through the older palroozoic slates, has a very important bearing ou the question of the occurrence of gold iu the interior of the North Island, as there is a probability that many other localities besides the Cape Colville peninsula will prove auriferous to a similar extent. I see no reason, however, to expect any extensive alluvial diggings in the Kavaka district, or that it will afford a field for the employment of a large mining population. — I have, &c, .Tames Hectoe. The Under Colonial Secretary. EXTRACT FROST DR. HECTOR'S INSTRUCTIONS. The range mliicu separates the Thames Valley from the Bay of Plenty 1 found to consist of a nucleus of uplianite slates interbedded with green breceiated and grey wacke slates, being part of the upper paleozoic series. Flanking and capping this nucleus is a great development of the following members of the tertiary series : — ( a). Brown coal formation, very local, (b). Quartzose gravels cemented so that they break awaj r in large b'ocks. (e). Waitemata series (pliocene), (d). Trachylic tuff', (e). Trachytie breccia. The palaeozoic rocks are cut by dykes of trachyte (granite of the miners), which is charged with auriferous and cupreous iron pyrites. They, moreover, . contain quartz veins, which aro also pyritil'erous and auriferous. The ohler rocks decompose very freely to laterite, and the fissures then contain secondary deposits of silica, manganese, &a, especially when near the supposed trachyte dykes, alongside o) which in some eases there would seem to have been fissures that were only gradually filled up by deposits from thermal wau-i's, giving rise to the banded, irregular, ami crystalline structure of tho lodes which is so characteristic of Coromandel. Tho composition of tho several rocks in the vicinity of the lodes at Coromandel shews their singular character, arising, I suspect, from all the .soluble matters of what was once a basic rock having been removed and replaced by .silica, and parlly by iron pyrites containing H°'d. Thai this mineral is the main source of gold is shown by a section of ihe lode ground L made in 1861, when I found that tho so-called quartz reels were contained between two varieties of tho pyritouu rock, the sulphurets having been removed from tho overlying rock, but- still remaining in the lower, the reef itself being a band of mullock containing kernels and geodes of quartz and carbonate of lime, and evidently formed by infiltration. A third manner in which quartz occurs in the district is in the trachyte tufas, but it is then more chalcedonic and crystalline, and associated with jasper and chert, and is nonauriferous, as proved by the numerous trials at Keoven'ti 1-Viut, Coromaudel. The older rocks present too limited an area in th*?, Cororuandel district to form the source of much gold by direct denudation as in theuouth of .New Zealand ; still, where they have beou decomposed to form the red

clay or laterite, and secondary minerals thereby formed, gold may bo among these. The gold in the case of Fatawni Creek, Cor<>inandel, uiust hare had a difiojvnt source from tke gold got in Driving Creek, ns its 1 value was £3 17s 6d per ounce, but siiolj du- ! posits seem to be very small and patchy, us only £200 worth was got, I believe, by Mr Turner, in 1863. I would not, therefore, reoommend as a guide in forming an opinion a§ to the prospecb of gold, the mere presence or absence of paleeozoic rocks, without at the game time taking into consideration their peculiar association with the pyritcms rocks above referred to. The .same paleeozoic rocks occupy a 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 ol quartz. 2. Search for the grey pyritiferous rock in the beds of the streams. 3. Areas where decomposition and siliceous infiltration have affected the rocka "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. 4i. 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 thai no gravels of miocene age, however purely composed of quartz, have yet proved auriferous, such for instance as the quartz cements along with tho brown coal formations. * (Signed) James Hector. JIEitOBANDUM CONCEUN'ING THE KOCK SPECIMENS ACCOMPANYING- CAPTAIN HUTTON'B REPOJIT. Thirty-eight specimens have been sent to illustrate the geology of the Jlaraka district, and present a similar character to tho rocks from Coromaudel. 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 subsianco of the stone, the matrix being a blue splintery quartz traversed by cracks. Respecting tho specimen from Barry's Creek, which is exceedingly rich, Captain Hutton remarks that it was broken oiF a specimen picked outYroin 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 Mnseum 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 ia 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, 17tli September, 1867. Sie, — I have the honor to report that, in accordance with your instructions, I proceeded to the Thames goldfield on the 3rd inst. On the 4th and sth I examined the sluicing operations in the Karaka Creek, and the various auriferous veins that had been discovered in the neighborhood. 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 thi: llth I sailed with Mr Commit sioner Mackay for Auckland iu his cutter, •and arrived there at 2 a.m. on Sunday, 15th instant. I enclose my report on the district I visitod together with a map and section. I also send by tho 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, R11.5., Director of the Geological Survey oi New Zealand. fei