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TUI MINE, TE AROHAf,

by L. Carter and C. H, Pharo

ABSTRACT

This paper deals with the history„ the geology, and a d e s c r i p t i o n of Tui Mine Te Aroha. The report i s aimed at providing a basis f o r a further more d e t a i l e d study of the Mine and i t s surrounding area. Tui Mine i s one of the few mines s t i l l being worked i n the Hauraki gold field, and i s the only one i n the area that has been worked as a base-metal p r o p o s i t i o n .

INTRODUCTION

Tui Mine i s located two miles north of Te Aroha town-ship, on the western flanks of the Kaimai Ranges. The present workings on numbers Four and Five l e v e l s cover an area of 150, 000 square f e e t . The newly opened number Three l e v e l has not been included i n t h i s study.

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In 1962 South P a c i f i c Mines L t d . , acquired the lease to prospect and evaluate the area as a base-metal p r o p o s i t i o n . Subsequently t h i s company has reopened the lower two l e v e l s of the o l d workings, and has prospected the lodes i n these l e v e l s by d r i v i n g along them and s t o c k - p i l i n g the removed ore and country rock. Future plans of t h i s company include the establishment of a f l o t a t i o n plant on the f l a t area at the j u n c t i o n of the mine road and the road leading to the N. Z. B. C. 'a T e l e v i s i o n repeater s t a t i o n on top of Mt. Te Aroha.

THE MINE

The mine has been developed on f i v e a d i t l e v e l s , which vary i n length from 30 to 1350 f e e t . At the time of w r i t i n g South P a c i f i c Mines Ltd. had reopened two l e v e l s , No. Four and No. F i v e , and were beginning to develop No. Three l e v e l .

In the upper l e v e l s , Numbers One and Three, the e a r l y workings were i n the form of open cuts and gopherings through oxi d i s e d m a t e r i a l and c e r u s s i t i c ore. This may Indicate the presence of a narrow, discontinuous o x i d i s e d zone i n the Tui ore body. Elsewhere on the surface the reef outcrops are unoxidised, while unoxidised ore also occurs underground i n Three, Four and Five l e v e l s .

GEOLOGY

The Kaimai Range forms part of a north-west trending b e l t of andesites of mid(?) and upper T e r t i a r y age. E a r l y workers i n the Coromandel - Thames - Te Aroha area d i v i d e d the v o l c a n i c s here i n t o three groups: the highly a l t e r e d and mineralised F i r s t Period andesites; the l e s s a l t e r e d and mineralised Second Period andesites; and the Third Period r h y o l i t e s and d a c i t e s . I f t h i s scheme i s adopted Tui mine area i s located i n the mineralised F i r s t Period v o l c a n i c s .

The country rock at Tui mine consist s of a l t e r e d and mineralised ("propylitised") andesite. Detailed t h i n s e c t i o n studies of t h i s rock w i l l be presented i n a future paper on t h i s area.

Two reefs are present: the north-easterly trending Champion Reef; and the east-north-easterly trending Ruakaka Reef. The expected ju n c t i o n of these two reefs has yet to be proved. The reefs diverge with depth and appear to steepen i n dip on t h e i r south-westerly extensions. The s t r i k e s of these reefs have been traced by surface outcrop f o r distances of 1500 feet f o r the Champion, and 2000 feet f o r the Ruakaka (Williams, 1964),

The cross cut on Number Five l e v e l from the Champion to the Ruakaka proves the persistence of these reefs with depth. Williams (1964) records that the Champion and Ruakaka reefs p e r s i s t over v e r t i c a l distances of 594 feet and 785 feet r e s p e c t i v e l y . Williams also described the reefs as " r e l a t i v e l y massive, hard quartz containing a p e r s i s t e n t core of sulphides from three inches t o , exceptionally, as much as three feet i n thickness. The reefs are separated from the r e l a t i v e l y hard country rock by a clay p a r t i n g , but the contained sulphide core i s frozen to the reef. "

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The purpose of t h i s i n v e s t i g a t i o n was to provide a b a s i s f o r a more d e t a i l e d study of the area. The r e s u l t s of a plane-table survey of the Number Four and Number Five l e v e l a d i t s and the road connecting them, made during a 1964 Geology Stage I I I f i e l d t r i p , have been checked and used here. The a c t u a l a d i t - l e v e l s were surveyed using the chain and compass technique.

HISTORY of the TUI MINE

O r i g i n a l l y known as the Champion Mine, i t was f i r s t opened up i n 1884 to provide a f l u x f o r the smelting of the Wairongomai gold ores of the Te Aroha Gold and S i l v e r Company. However, the high z i n c content of the ore rendered i t unsuitable f o r t h i s purpose. Attempts were then made to mine the Tui ore purely f o r i t s gold and s i l v e r content, but the r e f r a c t o r y nature of the ore made i t impossible to e x t r a c t economically the gold and s i l v e r by the methods then i n use. Even the "thermohyperphoric" method of t r e a t i n g r e f r a c t o r y ore, developed i n 1899 by the Rev. Joseph Campbell, f a i l e d on the Tui ore.

The e a r l i e s t owners appear to have been the Thames Lead and S i l v e r Co., but i n i t s e a r l y stages the mine passed through many hands. In 1889 three l e v e l s had been constructed and communication made between them on the main lode. An a e r i a l tramway was under construction to take ore 120 chain down the mountain to the f l a t s below. I t was planned that some of the ore should then go to the Te Aroha Gold and S i l v e r Company's smelter at Wairongomai; and that a packet of 200 tons be sent to England. A previous packet of 11 tons sent to England r e a l i s e d £6. 10. 0. per ton.

By 1893 the company was s t r i k i n g f i n a n c i a l d i f f i c u l t i e s s ince no s u c c e s s f u l and economical method of dealing with the r e f r a c t o r y Tui ore had been found. The Wairongomai smelter had only recovered 30% of the b u l l i o n from the samples sent from T u i , and i t was considered not worth sending any more. I t was then decided to wait f o r a plant to be erected by the nearby Crown Co, that would t r e a t ore by the more economical cyanogen process. This plant apparently f a i l e d , and i n 1896 the lease was obtained by The New Zealand Syndicate. The f o l l o w i n g year the Tui Gold-mining Co. acquired the lease. By t h i s time f i v e a d i t - l e v e l s had been opened on or near the Champion lode, and had been d r i v e n i n f o r distances varying from 30 to 270 f e e t .

The Tui Gold-mining Co. does not appear to have developed the mine any f u r t h e r ; the working of the area apparently being subject to the success or f a i l u r e of the treatment plant that was being erected to deal with the ores of the close-by Montezuma claim. This plant proved to be a f a i l u r e , and the Tui area was abandoned u n t i l 1902 when a l o c a l syndicate took up the claim. A few men were put on to e x t r a c t ore f o r t e s t i n g purposes. Although the r e s u l t s of these t e s t s are unknown, presumably they proved too poor to consider the resumption of mining.

Since then the claim has had a number of owners, and s e v e r a l changes of name. A l l e f f o r t s made to r a i s e c a p i t a l i n England and elsewhere to provide the expensive treatment plant f a i l e d .

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Cinnabar i s associated with the lode m a t e r i a l as druses i n the lode, and along the clay selvages* Limonitised q u a r t z - f i l l e d drusy c a v i t i e s i n the wall-rock near the lode are sometimes w e l l developed.

W h i t t l e ( i n Williams. 1964) described the Tui ore from polished sections as " e s s e n t i a l l y a coarse-grained aggregate of s p h a l e r i t e , galena, c h a l c o p y r i t e , and p y r i t e with subordinate f i n e r - g r a i n e d marcasite, tennantite, and c h a l c o c i t e i n quartz gangue. " and "minor secondary enrichment e x i s t s by v i r t u e of c h a l c o c i t e replacing the edges of cha l c o p y r i t e and s p a l e r i t e . "

CONCLUSION

With the advent of a plant f o r crushing and concentrating the Tui ore, fur t h e r development of the Tui Creek area as a base-metal f i e l d i s possible. More d e t a i l e d and concentrated prospecting could reveal other l i k e l y lodes or v e i n s . However, the steep and densely bushed nature of the country w i l l make t h i s d i f f i c u l t .

ACKNOWLEDGEMENTS

The w r i t e r s would l i k e to thank:

South P a c i f i c Mines L t d . , f o r permission to work on the lease, and to pub l i s h t h i s a r t i c l e .

Mr. M. Sprogue, f o r h i s help while the w r i t e r s were on the lease.

The Auckland U n i v e r s i t y Geology Dept., f o r the use of surveying and d r a f t i n g equipment.

Messrs. B. G. Jones and W. S. Hughes, fo r c r i t i c a l l y reading the manuscript.

Mr. & Mrs. L. Hodgson, f o r h o s p i t a l i t y extended to the w r i t e r s during t h e i r stay i n Te Aroha.

REFERENCES

DOWNEY, J . F. 1935. Gold-mines of the Hauraki D i s t r i c t , N. Z. N. Z. Govt. P r i n t e r P u b l i c a t i o n .

HENDERSON; J . and BARTRUM, J . A. 1913. The Geology of the Aroha Subdivision. N. Z. Geol. Surv. B u l l . 16.

N. Z. MINES RECORDS N. Z. MINES STATEMENTS. WILLIAMS, G. J . 1964. "Economic Geology of New Zealand. " Melbourne. Austr.

I n s t . Mining & Metallurgy.

REQUEST FOR RESEARCH MATERIAL

M a t e r i a l i s required f o r working i n v o l v i n g the r e v i s i o n of the New Zealand Aradidae (Order Hemiptera). These i n s e c t s are commonly known as f l a t bugs or bark bugs and are u s u a l l y found underneath the loose bark of dead t r e e s , or i n l e a f l i t t e r . They are q u i t e s m a l l , many of them being only a couple of m i l l i m e t r e s long, although our l a r g e s t species i s over 1 cm. Nearly a l l species are very f l a t t e n e d , some being paper t h i n . This c h a r a c t e r i s t i c and t h e i r d u l l brown or mottled c o l o r a t i o n renders them very inconspicuous i n t h e i r n a t u r a l surroundings.

New Zealand has a very r i c h fauna of Aradidae; i n f a c t i t has been s a i d that t h i s country stands as a n a t u r a l storehouse of Aradid types unequalled by any other i s l a n d or continent.

Associate-Professor J . G. Pendergrast, of the Department of Zoology, would be very g r a t e f u l f o r any specimens which c o l l e c t o r s discover. They could be sent dry ( i n s o f t t i s s u e paper) or preserved i n s p i r i t . Information about the l o c a l i t y , place where they were l i v i n g , date and the c o l l e c t o r ' s name would be appreciated.

An Aradid Bug