Gold mining in Hauraki and Coromandel
Located a short distance to the southwest of the major gold-mining town of Waihi in northern Hauraki, the proposed historic area is closely connected with the development of gold mining technology on the Coromandel/Hauraki goldfields, and particularly the use of cyanide extraction processes and dredging as ways of maximising production in the late nineteenth and early twentieth centuries.
Gold mining formed one of the mainstays of the New Zealand economy in the nineteenth century, accounting for more than half of the country's exports in 1871 and still remaining at 12% of total exports thirty years later. Although a large proportion of early exploitation occurred in the South Island, gold extraction in the Hauraki and Coromandel regions grew steadily as a percentage of national production through the 1880s and 1890s as easier sources for exploitation became depleted. From 1905, the Hauraki/Coromandel goldfields became the most productive in the country, a position they retained throughout much of the twentieth century. Waihi, in particular, was at the epicentre of technological developments during the late nineteenth and early twentieth centuries, when it was considered 'the outstanding goldmining enterprise in New Zealand.'
The first official discovery of gold in the Coromandel occurred at Kapanga in 1852, although the earliest workings were soon abandoned due to increasing regulations, poor returns and friction with local Maori, who became reluctant to allow mining on their land. In spite of the formal declaration of the Coromandel Goldfield in 1862, it was not until after Maori resistance was weakened by the third New Zealand (or Waikato) War of 1863-1864 that prospecting expanded in earnest. Major discoveries were initially made in the western part of the Coromandel Peninsula, at the mouth of the Kuranui Stream in 1867 and Tapu Valley in 1868, leading to a dramatic influx of Pakeha. Negotiations with Maori leaders to open up mineral resources further east were declared completed by the government in 1875, when the Ohinemuri district was designated a goldfield. Reefs were soon found at Owharoa (1875) and the Waitekauri Valley (1875), with further prospecting occurring as far east as Waihi in northern Hauraki by 1876.
Waihi and the Waihi Gold Mining Company (WGMC)
Located in the eastern part of the Ohinemuri Goldfield, Waihi formed part of the lands of the Ngati Tamatera, who had resisted the encroachment of mining activities in negotiations during the 1870s. The first gold was found in a quartz reef at Pukewa (later Martha) Hill in 1878, and by 1880 individual workings were in operation around the outcrop. The operations expanded rapidly, and by 1900 it was said that 'miners huts and cottages were spread over an area of about three miles each way.' Five years later Waihi was the largest settlement in South Auckland with nearly three times the population of Hamilton.
Although prospecting was initially carried out by individuals or small groups of miners, the presence of gold in comparatively inaccessible quartz seams led, as elsewhere in the Coromandel/Hauraki goldfields, to the rapid arrival of larger companies who were able to extract gold from reefs more cost-effectively. This trend was initially evidenced by the registration of the Martha Extended Gold Mining Company in 1883, and from the late 1880s by interest from overseas-based operations with large amounts of capital available for investment.
The most important of the latter was the Waihi Gold Mining Company (WGMC), formed in London in 1887 specifically to exploit mineral resources at Waihi. The Company rapidly bought up a number of mines in the vicinity of Rosemont Hill, where their investment of £12,000 for plant is considered to have heralded the arrival of large-scale mining in the district. The WGMC's arrival in New Zealand reflects a pattern of increasing British private investment in imperial territories during the late nineteenth and early twentieth centuries and the continued internationalisation of the goldfields. A prime mover in the creation of the Company was the Auckland-based entrepreneur Thomas Russell (1830-1904), who has been described as 'arguably the outstanding commercial figure in nineteenth century New Zealand.' Russell's son, Thomas Henry Russell (1858 - ?), recognizing the potential of the adjoining Martha Mine, purchased this and certain other properties at Waihi, onselling to the WGMC in 1890.
In 1893, the WGMC adopted the cyanide process, which had initially been trialled by New Zealand Crown Mines at nearby Karangahake in 1889, the first time in the world that the method had been used on a large-scale commercial basis. The use of cyanide was particularly effective as a way of extracting gold from the quartz found at Waihi. Production was rapidly expanded by the WGMC, reaching a peak in 1909, when almost £1 million worth of bullion was extracted from the Martha Mine. As part of the expansion of the Company's activities, a new battery complex was erected at Waikino, a short distance to the west of Waihi, to process the growing amounts of mined ore. Construction of the Victoria Battery began in 1896 and was largely completed by 1898, forming the largest facility of its type in New Zealand.
Development of the Ohinemuri River site by the Waihi Gold Mining Company
A major reason for the Victoria Battery being built outside Waihi was to take advantage of the energy-generating potential of the Ohinemuri River, on which the new plant was situated. As part of the works, the WGMC created some 16 km (10 miles) of water races and 8 km (5 miles) of tramway to service the complex. Land upstream of the plant, at the confluence of the river and the Waitete Stream, was earmarked for a masonry dam and a water race to help power the battery. A tramway between the battery and the Martha Mine in Waihi was projected to run along the southern side of the river until a point just upstream from the dam, where the line then crossed onto the northern bank. The tramway was to transport quartz from the Martha Mine to the Victoria Battery for processing, and return with processed material. Until the plant was fully functional, it also assisted with the construction of the battery complex.
Early history
Immediately prior to WGMC's works on the area proposed for registration, the land to the south of the river was described as 'supposed unoccupied ground', while that to the east of the Waitete on the river's northern bank was subject to a claim by a James McWilliams in 1895. Property to the west of the stream had been granted to Mary Jane Nichol a year previously.
It is uncertain if there had been any earlier, Maori occupation of the site, although it has been suggested that low ground beside the Waitete Stream close to its confluence with the Ohinemuri may, on the basis of its type and situation, have seen prehistoric settlement. No evidence of Maori occupation was noted during earthworks associated with the construction of a dwelling on higher ground to the east of the stream, carried out in 2003. Early photographs of the site suggest that it contained few trees by the time that the WGMC's works were carried out in the 1890s, presumably because of heavy felling associated with the need for fuel and structural timber by the mining industry. It did include areas of low scrub.
The land proposed for registration incorporates a well-preserved part of the tramway between Waihi and the Victoria Battery, including the site of one of its bridges, the uppermost part of the Ohinemuri water race and the Ohinemuri dam.
Tramway
The tramway appears to have been among the earliest works linked to the formation of the Victoria Battery, perhaps because of its usefulness in transporting necessary materials for the construction of other elements. When completed, it formed an 8 km (5 mile) length of track, which, with the exception of one up-grade stretch of 1:90, ran downhill from the Martha Mine to the battery site. The tightest curve on the line had a 120m (6-chain) radius, while the overall gauge was 0.84 m (2 feet 9 inches) wide.
Construction work on the tramway may have begun in 1895, as by March 1896 it was reported that a third of the distance of the line had been formed. A year later, upwards of 4.8 km (three miles) had been laid with kauri sleepers and iron rails, glazed earthenware pipes used to form culverts, and swampy areas drained. The locomotive 'Ohinemuri' was also ballasting the line with rhyolite that was found alongside the railway, about 800 m (½ mile) from the battery, and was hauling building stone to the construction site at Waikino. The chief engineering feature on the route was a narrow rock cutting 9 m to 12 m (30 to 40 feet) deep.
Within the area proposed for registration, works included cuttings, embankments and the erection of a substantial timber bridge across the Ohinemuri River. The latter was known locally as the Black Bridge and was the largest of several structures along the tramway, including those traversing smaller streams. Work on these bridges was evidently well-advanced by March 1896 and the Black Bridge, at least, appears to have been completed by March 1897. The Black Bridge was described as being of strong truss construction, being upwards of 56.4m (185 feet) in length and 9.3m (30 feet 6 inches) high from water level to decking. It was built of heart kauri and totara.
The tramway was almost certainly fully complete prior to operations beginning at the Victoria Battery in February 1898, being employed to transport ore to the battery by a steam locomotive hauling 40 side-tipping ore trucks. The partially processed product was transported back to Waihi to be refined. The line was also used to transport coal from Waikino to Waihi for the WGMC. The configuration of locomotive and ore trucks was known as a 'rake' hence the tramway was generally called the 'rake line'. After 1899 two rakes worked on the line at any given time.
The Ohinemuri Water Race
The Ohinemuri water race was built concurrently with the tramway construction, dating mostly to 1896-1897. It was one of three separate systems established to power machinery at the Victoria Battery, and provided low-pressure energy to drive water turbines to power the battery stamps. The race was built at the same time as the Waitekauri River system, which provided high-pressure energy for Pelton wheels to power other machinery on the site. The third system, from the Taieri Creek, was developed in 1899, providing a further high-power energy source for driving stone-breakers used in the wet crushing process then being adopted at the battery. The latter also supplied the plant with clean water. The races formed an important part of the profitable operation of the Victoria Battery, especially prior to the advent of relatively cheap hydro-electric power from the Hora Hora scheme.
Planning for the Ohinemuri race began at an early stage, with a survey of the proposed routes for both the Ohinemuri and Waitekauri systems being completed to the foot of Thorpe's Hill,the site of the proposed battery, by the end of March 1895. A year later the position for the new 100-stamp mill had been fixed and extensive preparations made for erection of the plant. The race was to be 6.6 km (4⅛ miles) long, with its source slightly downstream from the Waitete Stream confluence. Water was to be carried wherever possible through a low-maintenance channel in the ground that measured approximately 4 m (12 feet) wide x 1.5 m (4 feet 6 inches) deep. Trestled flumes were to bridge ground depressions and, in two places, the Ohinemuri River. Apart from a short section on the northern bank of the river, the line of the race lay close to its southern bank. The total fall was 16.4 m (54 feet).
Construction of the race appears to have begun in 1896 and was largely functional by December 1897, including its intake within the area proposed for registration. At that time, it was reported that the two large arch-supported timber flumes crossing the Ohinemuri River had been completed while water had been let into the race and allowed to run half its length. Slips and leakages were minimal, the bulk of the race having had a summer and winter's weathering. The contractors had also almost completed a 144 m (475-feet)-long iron siphon pipe required to take the race across swampy ground, encountered halfway between the dam and the battery. The race was in a sufficiently forward state to allow it to be used as soon as required.
The Dam
As part of the Ohinemuri system, a masonry weir was constructed on the Ohinemuri River, approximately 150 m downstream from its confluence with the Waitete Stream. This coincided with the inflow at the eastern end of the water race, allowing a more regular and controlled amount of water to be taken into the system by creating an expanse of deeper water within the river. The dam was constructed in 1897, during the latter parts of the works relating to the race construction. A report for the year ending in March 1897 refers to the dam in the future tense, noting that 'it will be a strong and solid structure of masonry', to be erected at a cost not considerably greater than that of a timber dam. Its position is marked on a survey carried out in July 1897, and a report for the year ended December 1897 states that the work had been finished.
Constructed of coarse-hewn masonry, the 40 m-wide weir had 5m-high abutments at either end and a crest topped with timber, possibly railway sleepers. A sluice gate close to the southern end of the weir controlled the flow of water into the race. Apart from a smaller masonry dam at Mangakara on the Waitekauri system, most other dams providing energy to the Victoria Battery were of timber construction. Masonry was justified at the Ohinemuri intake to avoid potential failure of the structure, which would have caused serious damage to dams, bridges and flumes further downstream. The stone is thought to have been quarried from a site alongside the tramline about 800 m (½ mile) from the Victoria Battery, facilitating loading and transport to the weir site. This deposit readily yielded blocks of rhyolite approximately 300 mm (1 foot) square.
The combined cost of the Ohinemuri and Waitekauri races amounted to ₤14,000, a very substantial sum. Works on the Victoria Battery by September 1897, including its associated elements such as the dam, were considered to have cost £60,000 with an additional £20,000 required to complete the task. Due to the costs incurred, the capital of the company was raised from £160,000 to £320,000 after an extraordinary special meeting had been called in London to discuss the project. While these amounts reflect the very large levels of foreign investment, profits were also expected to be high and during the period 1895-1899, the WGMC paid out 40% in dividends to its shareholders. The value of the race to the works was such that it was maintained for the life of the Victoria battery and continued to contribute power until the plant's closure in 1952.
Gold Dredging at the Ohinemuri site
Dredging discharged tailings in the Ohinemuri River at its confluence with the Waitete occurred soon after construction of the works associated with the Victoria Battery. Mine companies frequently discharged their waste into nearby watercourses as a way of removing material from the site at low financial cost. After the discovery of the cyanide process, it was recognized that these tailings could potentially be re-processed to extract further gold. Re-processing eventually raised gold recovery rates from 30%-40% to as much as 98% in ideal conditions, thanks in part to technological advances developed on the Ohinemuri.
Gold dredging took place extensively in the South Island from the 1890s peaking in 1903 when there were 201 dredges in use in New Zealand. Dredging for gold only took place, however, at four sites in the North Island. Two of these were foreshore claims, comprising the Langford's Syndicate - which started trials in December 1911, and the Thames Foreshore Dredging works, which also commenced in 1911 but whose treatment of the tailings was carried out at the Moanataiari battery. Only two river gold dredging operations in the North Island are known, of which that at the confluence of the Waitete Stream and the Ohinemuri River is the earliest.
Waihi Dredging Company
From 1890 onwards, it was generally known that tailings from the Martha Extended Gold Mine battery, which had been discharged into the Ohinemuri River from 1883, were of considerable value. The Mining Act 1891 legitimised the practice of discharge of tailings into the Ohinemuri, proclaiming the river to be a sludge channel. This further increased the tailings available to later dredging operations downstream from Waihi. The construction of a dam at the confluence with the Waitete Stream in 1897 may also have raised the potential of dredging operations, restricting the downstream flow of tailings and affecting the long-term viability of the dam without intervention.
The first operations on the Ohinemuri were carried out by the Waihi Dredging Company (WDC), which was formed in 1897 by E.H. Barber with capital of £5000. In June 1898, the company was issued with licences by the Goldfields Warden's Office at Ohinemuri for two areas, each slightly over 5.25 ha (13 acres). The area in the immediate vicinity of the dam had been surveyed for the company the year before and appears to have been the subject of a third claim. It is unclear if the latter was ever formally licensed, as the survey appears to have been withdrawn at the same time that the other two claims were granted and no third licence is noted as having been issued prior to the end of March 1899.
Some dredging activity may nevertheless have been carried out on the Ohinemuri at its confluence with the Waitete Stream, immediately upstream from the dam. Structures on the north bank of the river, between the Waitete and the WGMC tramway appear to be indicated on photographs taken of the construction of the dam in 1897 or 1898. Located on the site of later dredging facilities, these may include an elevator and an associated facility. The land on which they are situated had been the subject of an application by a Mr James McWilliams in 1895, although the first transaction in land records was a 21-year occupation lease issued in 1911, after the later dredging plant had been relocated to Paeroa. As most surface areas for mining plant and buildings were held under 'Special Site Licences', there is no reference to the presumed WDC plant in land records for the site.
Sands Tailings Syndicate and Ohinemuri River Syndicate
By early 1902 the Waihi site is said to have had a new 'owner', Frank Rich. Otago-born Rich had been the General Manager of the Woodstock Gold Mining Company at Karangahake in circa 1900, after training and practicing in California and Colorado. After resurveying the Waihi Dredging Company's claim for the Waitete junction in March 1902, his application for the claim appears to have been granted. By August, the Sands Tailings Syndicate, with which Rich was presumably associated - had begun treating tailings deposits on the banks of the Ohinemuri River, 'commencing at a point in the vicinity of the Waihi Company's Waikino dam and the junction of the Waitete Creek.' Mines reports for the year ending 31 December 1902 noted under the heading 'Ohinemuri River Claims' that Mr Rich and party had taken out several claims in the bed of the Ohinemuri, and having obtained encouraging results from tailing samples were in the process of erecting an up-to-date plant for processing the tailings.
Other reports for the same period state that the Ohinemuri River Syndicate had pegged out several claims and 'are erecting a plant by the Waihi Company's dam, which is expected to be ready for working about the end of March. The promoters have spent between ₤3,000 and ₤4,000 [and] about 20,000 tons of tailings are supposed to have accumulated in the dam alone, so that if they are payable the syndicate should be successful in their enterprise. About 50 tons will be treated daily.' The relationship between the Sands Tailings and Ohinemuri River Syndicates is currently unclear, although the plant is almost certainly the same.
A year later, houses and machinery had been erected, and costs had risen to ₤7,000 -₤8,000. Evidently owned by this time by Messrs F.C. Brown and [J.A.?] Thompson, the plant is said to have started operation late in 1903. As a new venture much experimentation occurred, notably as tailings required fine grinding to allow the cyanide solution to dissolve the bullion. In 1904, a small tube or flint mill was erected that could finely grind up to 100 tons of tailings per week, but this led to further difficulties as the fine material required perfect agitation in the cyanide tanks to enable a high extraction of bullion.
Various air agitation tanks were trailed before Brown and Thompson invented their own system, which was patented in New Zealand, Australia, the USA, Mexico, and Transvaal. These are said to be the now-famous Brown-McMiken 'B & M' agitation tanks which were also known as Pachuca or Pachucca tanks. Essentially a tall cylinder with a conical bottom through the apex of which air was forced, these tanks were used in New Zealand and internationally to treat very finely ground ore (known as slimes).
It is not disputed that F.C. Brown was an inventor of the B & M tank. There is some doubt, however, as to whether he invented the technology while developing the plant to process dredge tailings near Waitete Stream (as suggested in the Report of the Inspector of Mines, Thames for the year ending 31 December 1904), or whether the first tank was designed and erected in 1902 when Brown was the general manager at Komata Gold Mines, at Komata (as stated in James Park's The Cyanide Process of Gold Extraction (published in London in 1913). Lodgement of the patent application in May 1904, after the tube mill had created problems earlier in the year, would appear to suggest that the invention was perfected at the Ohinemuri site.
While earlier structures may have existed on the site, the dredging plant by this time was made up of a series of substantial corrugated iron buildings along with tanks and elevators immediately east of the confluence of the Ohinemuri River and Waitete Stream. A bucket-chain elevator removed the tailings from dredge barges, depositing the material in a holding tank in front of the processing plant. From the tank, the tailings were elevated by a bucket-chain into the plant where they were cleaned and sorted for size. Eventually tube mills were used to grind the material to the required size. From the tube mills the slurry was processed in six large vertical air agitation tanks, which stood beside the main building. Other buildings on the site included an assay room, boiler house and dwelling.
Despite the development of a successful process, the dredging plant was found to be commercially unsuccessful by 1905, despite the large amounts of capital invested.
Waihi Paeroa Gold Extraction Company
In October 1908 the venture was sold to the Waihi Paeroa Gold Extraction Company (WPGEC), which installed new machinery including four tube mills, agitators, concentrators and a new air compressing plant. The overhaul of the plant and installation of the new machinery took nine months and cost £16,000. After 18 months of experimentation with grinding and treatment processes, which played a vital role in improving appliances for lifting, grinding and cyaniding, the plant ultimately proved that it could be viable. Figures for 1909 show that 23,950 tons of tailings were reprocessed and 30 men were employed.
On 4 March 1910 a public company was formed, the Waihi Paeroa Gold Extraction Company Limited, as management planned to erect a new plant at Paeroa. This was to be modeled exactly on the processes that had been perfected at the old plant, but had four times the capacity. The Waihi plant closed that same year after processing 35,034 tons of tailings for a return of 36,770 ounces of bullion, valued at £14,615. In April 1910, tenders were advertised for dismantling the Waihi plant at Waitete Stream for removal to the new site near Mill Road, Paeroa, and much of the equipment and suitable buildings were presumably relocated shortly after this time. The Company operated the new facility a short distance from Paeroa on the Ohinemuri River from March 1912 until 1918 when the firm went into liquidation. This complex was the only river-based gold dredging plant in the North Island other than the Waihi plant.
Subsequent modifications to the area
Changes to the WGMC network
Modifications were made to the WGMC's network within the proposed area of registration while the Gold Dredging Plant was still operational. With production at the Victoria Battery expanding far beyond that originally anticipated, the power supply soon proved inadequate. In 1899 a 520-horsepower steam engine capable of driving a total mill of 200 stamps was on order at the plant, while a third turbine of 100-horsepower, powered by the Ohinemuri lower pressure water race, was erected and commissioned in August 1903. The capacity of the race was increased at this time when its banks were heightened and strengthened.
Increased production also led to alterations to the tramway, with a loop line, outside the area proposed for registration, being created to allow two locomotives to pass. To cope with the large amount of traffic, curves on the line were strengthened in 1902 by adding puriri sleepers with bed plates and flange bolts, while some of the old 40 lb iron rails were replaced by new steel rails of the same weight the following year. During 1903 the rake was carrying a large amount of general stores, coal, broken metal, sand and cement for the foundations of the new pumping engine at the Martha Mine's No. 5 shaft, as well as machinery for the Waihi and Union Mills. By the end of 1904, the last of the old 40 lb iron rails had been replaced by steel, and when the locomotive 'Waikino' came into service in 1905 culverts and bridges, including, presumably, the Black Bridge, were strengthened to cope with anticipated increased weight. The following year part of the track was laid with heavier sleepers.
Rapid developments in metallurgical methods, including the introduction of tube mills, concentrators and vacuum filtration, continued to increase energy demand at the battery. From about 1908, water power was being supplemented by a producer-gas plant and in 1913 hydro-electricity from the WGMC's Hora Hora scheme on the Waikato River was employed. The departure of dredging activity immediately upstream from the dam in 1910 may have increased the likelihood of flooding. In 1911, the 'wings' of the dam were carried up an additional 1.8m (6 feet) as a protection against high floods, at which time the sluicing mechanism at the intake of the race also appears to have been modified.
All of these elements continued to operate until 1952, when the plant closed down. At some time, probably in the 1950s, an unsuccessful attempt was made to dynamite the dam, or at least the outlet control. Locomotives and other usable scrap from the tramways, including possibly the rails, were cut up and sold. By 1963 the railway had become hard to trace as the land was ploughed and, in the Waihi Borough, buildings were erected over the alignment.
The development of farming
As the district of Waihi was gradually converted from mining centre to a rural community, scrub was cleared and dairy farming was introduced. In 1914 the Crown granted a 66-year lease to Waihi farmer William Follett for the 112-acre site through which the tram line route passed immediately to the south of the masonry dam on the Ohinemuri River. Charles Snow took over the lease in 1919 and obtained the freehold for the property in 1943. Although the land changed hands three times over the following 60 years, it remains in farming use today. Similarly, the 20.2 ha (50 acres) taken up by Jane Nicholl on the west side of the Waitete Stream was sold to a Waihi farmer, William Dean in 1910. It remained in the Dean family until 1943 and continues to be used for farming.
In 1911 Waihi farmer Donald Gallie took a lease over 1.6 ha (4 acres) on the east side of the Waitete Stream, the land formerly occupied by the gold dredging plant. He freeholded the land five years later. Waihi farmer Bill Lawrence incorporated the land into a 9.5 ha (21 acres) holding in 1971, which was enlarged by a further 1.2 ha (3 acres) in 1984. In 1985, parts of the gold dredging plant may have re-contoured with a bulldozer. The site of the former dredging plant was part of 4.9 ha (12 acres)purchased by the Hauraki District Council in 1993, the western part of which has been converted into a reserve. The land fronting Lawrence Road was developed as a residential subdivision after 2001, including a plot over the eastern part of the dredging plant remains, on which a dwelling was erected in 2003.
Other modifications to the area have included damage to the northern abutment of the dam during a severe storm, possibly in 1981, which was repaired, while a narrow gap has also been bulldozed through part of the tramway embankment immediately to the north of the Ohinemuri River. Apart from the dwelling and reserve on the site of the Gold Dredging Plant, most of the rest of the land is currently used as pasture.
