THE Thames Guardian AND MINING RECORD. FRIDAY, DECEMBER 1, 1871.

Thames Guardian and Mining Record, Volume I, Issue 48, 1 December 1871, Page 2

THE Thames Guardian AND MINING RECORD. FRIDAY , DECEMBER 1, 1871.

The “‘reports of geological explorations during 4870-71, Avith maps and sections,” by Dr Hector, F.lt.feh, published by the New Zealand Government, contain many interesting notes on the Thames and Coromandel goldfields. We propose referring to them from time to time, for the purpose of placing before our readers the conclusions of scientific men on the geological formation, and processes of mining adopted in these districts.

The first section, having a local reference, is “ Notes on the Thames Goldfields, by 8. Heydelbach Davis, F.C.S., F.G.8.” r J'he notes on the Thames goldfields, together with “ Notes on certain portions of the Nelson Province,'’ which appear in the present volume, are the hast that will ever issue from the pen of Mr Davis, who, as our

readers! may r ,remember, Avas recently droAvned iii , a river in the Middle Island, ’Avuibc in the discharge of his duty in leohujbctioh with the Geological Department. . His loss is a public one ; and, alllionglronly a short time associated Avitli Dr Hector, the Director of the Geological Department, he had rendered important service to the cause of science, and gave promise of greater future usefulness. The second section contains “ Notes on the processes in use in the Thames Mining District for the extraction of gold from the matrix,” by Mr Skey, Analyst of the Geological Department. The third section is a report “ on the Geology of the Cape Colville District,” by Dr Hector. It likcAvise contains a report “on the Geology of Coromandel,” by Captain Tlutton, avlio has succeeded the late Mr Davis, as Assistant Geologist, at Wellington. We shall refer to the second section to-day, namely, that by Mr Skey, “on the processes in use in the Thames mining district for the extraction of gold from the matrix.” It is divided into twelve heads or sections, and occupies sixteen pages of closely-printed matter. Mr Skcy Avrote in August, 1870, more than tAvoire months ago. He begins by stating “ that great difference of opinion prevailed as to the actual amount of gold that escapes with the tailings from the mills, and that this and several collateral questions could only be determined by experiment.” To determine these points, a small laboratory Avas erected at GraliamstoAvn, in Avhieh Mr Skey commenced the investigation, in June of last year. His attention Avas specially directed to the folloAving points : 1. The actual loss of gold in the course of extraction of the metal from the ore, at the different mills. 2. The cause of this loss, and lioay far it could be remedied. o. The manner of combination of the gold, in different forms of matrix. 4. The effect of the use of sea water, and Avatcr pumped from the mines, upon the machinery employed. Mr Skcy proceeds to narrate the precautions he used in sampling the tailings, Avhieh, Avitli tAvo or three exceptions, Avas done under his immediate personal superintendence. “ Only tAvo or three samples Avere taken from the settling-pits, as tailings so deposited Avould be more than usually concentrated, and so vitiate the results of tlxoir analysis. The rest of the tailings were collected, either from the large heaps of tailings Avhieh had accumulated in the yards round the various batteries, or else directly from the shoots discharging these, Avliile the flatteries Avere at work.” The heaps Avere each sampled tAvcnty or thirty different places, on all exposed sides, live or six inches beloAV the surface. “ All samples Avere well mixed, and dried before examination. The results given, therefore, refer to the respective samples Avhen air-dried.” Of the two iilans of sampling, Mr Skey prefers that from the shoot, although more tedious, as the analyst “can alloAV Avith more certainty for the proportion of fine substances carried away in suspect ion by the Avatcr.” Having stated these preliminaries, Mr Skey proceeds to detail the mode of determining the yield of gold afforded by re-amalgama-tion of tailings. He used a hand burdan, similar in shape to the ordinary ones, and fixed at about the usual inclination. No chemical agent Avas used to assist in amalgamation by the hei'dan. The Avliole of the quicksilver Avas retorted off' from the several amalgams obtained, and no leather Avas used, as the use of leather “must have seriously effected the correctness of the returns.”

The folloAving list slioav the actual results of the several experiments :

Lid of Results obtained by the Analysts far Cold, of Tailtttys Jrotn various Hatter'es , situated in the Thames Gold-field District.

Onohuuga--by berdan, klwt; by mortar, Idwt Mgr ; yield loz, nearly; taken from heap ; character of tailings, moderately fine. Criterion—(Shamrock: by berdan, 2dwt3gr; yield unascertained, small; from heap; mod. line, pyritous, heap 500 tons.

Una—by berdan, 2dwt Ggrs ;by mortar, Idwt 20gr ; after roasting, Idwt 17gr ; yield, J to 1 Joz ; from heap ; mod. fine, pyritous, heap 300 tons.

Bull's—Berkeley Castle : by berdan, 2dwt 10gr: assay, 2dwt 18gr; yield, ljoz ; from heap ; mod. fine, pyritous, heap 40 tons. Bull s—Berkeley Castle : by berdan, 2dwt llgr ; yield, ljoz ; from shoot.

Onchunga—Scottish Chief : by berdan, 2dwt llgr ; yield, loz ; from shoot. Tararu—Golden Grown : by berdan, 2dwt llgr; by mortar, 2dwt 17gr; after roasting, 2dwt llgr ; yield, 12dwt to loz ; from heap ; mod. fine, very pyritous, heap LOOOtons. Prince Alfred—Young American: by berdan 2dwt 22gr ; by mortar, 2dwt 20gr; yield, ljoz ; from heap ; fine, colour reddish, heap 200 tons.

Kuramii—by berdan, Sdwtlgr; by mortar, 4dwt 7gr ; yield, l joz ; from heap; mod. fine, very pyritous, heap 200 tons. Kurauui—by berdan, 3dwt 16gr ; yield, ljoz, ; from shoot; fine, colour red.

Soutcr’s—Flying Cloud : by berdan, 3dwt 20gr; by mortar, 4dwt; after roasting, 6dwt 17gr; assay, Bdwt 12gr ; yield, 2oz; from shoot; fine, very pyritous.

Tramway—Just in Time : by berdan, 4dwt; by mortar. sdwt 17gr ; after roasting, 7dvvt 7gr ; from shoot; line, very pyritous. Hauraki Mariner’s Reef: by berdan, 4dwt 7gr ; yield, 2oz ; mod. fine, very pyritous, 05 tons.

Moanataiari—by berdan, 4dwtl4gr; yield, Joz ; from settling pit. Criterion—Waitcmata : by berdan, 4dwt 14gr; assay, Bdwt 23gr; yield, loz; from shoot.

Flora Macdonald—Ladybird and Hand of Friendship: by berdan, odwt lgr; yield, Odwt; from shoot; mod. fine, feebly pyritous, colour reddish.

Hunt’s—by berdan, sdwt 2gr ; by mortal 1 , Bdwt Mgr ; yield a little over 2oz; from heap : very line, had been calcined. Kurauui —Long Drive : by berdan, sdwt 9gr ; yield, 2uz ; from heap ; very pyritous. Prince Alfred—lnverness: by berdan, sdwt 17gr ; by mortar, Odwt 2gr ; yield, 4 to soz : from heap ; fine, colour red, quantity 50 tons. Golden Crown—by berdan, sdwt 19gr ; by mortar, 10dwt2()gr; after roasting, lOdwt 22gr ; assay, 12dwt 3gr; yield, \oz ; from heap ; veiy pyritous. Russell s— Little Nell : by berdan, sdwt 20gr ; by mortar, 7dwt 4gr ; yield, {oz; from shoot; mod. line.

Hunt's—by berdan, Odwt lOgr ; by mortar, odwt 23gr ; yield, 2oz ; from shoot ; fine. Una—by berdan, 7dwt Mgr; from shoot; very fine, feebly pyritous, reddish. Hague Smith’s—by berdan, 7dwt 21gr ; assay, Bdwt lgr; yield, loz; from shoot; fine, feebly pyritous, reddish,