THE OTTERY MINE, TENT HILL NEAR EMMAVILLE NSW AUSTRALIA

THE OTTERY MINE, TENT HILL NEAR EMMAVILLE 

NSW AUSTRALIA

The site in December 1967

The Ottery Mine is one of the few places in NSW where the public can go and get a good idea of what went on at a mine in “the good old days”. Usually, such sites are out of bounds, being on current mining leases or private land or considered too dangerous to allow people in. The Ottery is different – a lot of money has been spent to make the old mine site accessible and provide good information so you can see for yourself how it all came together.

The mine is close to the Tent Hill-Torrington road just a few km from the old tin mining town of Emmaville, itself about 40km from Glen Innes. For more information on how to get there and what there is to see, I recommend the following websites: Aussietowns – Emmaville (here), the Northern NSW site (here) and Aussie Sapphire’s Blog (here).

The site in May 1991

Before I move on to more technical stuff, here are few personal observations which might enhance your visit.

I first saw this place in December 1967. The main features haven’t changed greatly since then – the chimney, the condensing chambers, the damaged environment (though this has been improved a lot by the mine site rehabilitation that has gone on since then.) In 1988 I collected specimens of pyrite and arsenopyrite there. You can still smell the sulphurous odour around the site. I observed (on the right near the car park) that there were a number of decaying wooden barrels which still contained a whitish substance. Maybe they are still there and perhaps it is refined arsenic oxide (as I first thought). More likely it is cement, which was delivered in barrels before the double paper bags of more recent years.

May 1991

On several occasions since then, I have been underground in the old workings (a potentially very dangerous thing to do), though most openings were blocked off even then. It was a real eye opener to catch a glimpse of the conditions in which the old time miners worked and to see the mineral veins in their natural condition in places in the rock walls.

As you will soon discover when you start reading about the Ottery, there were two main stages in the history of the mine. The tin stage began during the mining boom at Vegetable Creek (now called Emmaville) which commenced in 1872. Prospectors scoured the district, one of whom (Alexander Ottery) discovered the outcrop of the cassiterite-bearing veins sometime between 1875 and 1881. The mine was opened up in 1882 and the Glen Smelting Works was established to extract metallic tin. The site of the smelters is at the junction of the Emmaville-Deepwater and Torrington roads (Tent Hill).

From The Mineral Industry of NSW (EF Pittman 1901)

Eventually mining tin became unprofitable and the site passed into the hands of the firm William Cooper and Nephews (Australia), who then mined the arsenopyrite ore bodies to produce arsenic oxide which was widely used in the manufacture of sheep dip (1920’s on). This is the time when the surviving condensation chambers and chimney were constructed. There has been a lot of investigation of the site in more recent times and on several occasions when passing by on the way to Torrington I’ve observed drilling in progress on the hill. No doubt the price of tin is the key to any future mining there.

From The Tin-Mining Industry in NSW (JE Carne1911)

You could never call the geology of a site like this “simple”, but basically there are at least 5 quartz veins associated with fissures in a body of granite which intrudes claystone and tuff. This granite is probably related to the Mole granite to the north around Torrington. Arsenopyrite (FeAsS) and cassiterite (SnO₂) were the main ore minerals extracted, but pyrrhotite (Fes) and pyrite (FeS₂) are also present. As is common with such ore bodies, many other minerals have been identified in the ore, but are unlikely to be found as hand specimens.

To gain a better understanding of this place, and to see how it fitted in to the wider mining field, there are many good references you can download. Here are just a few.

A compendium of documents assembled by the Geological Survey of NSW may be found in DIGS (reference number R00045777). Doing a search in DIGS using the location “Tent Hill” and keyword “Ottery” will turn up much more. Of particular interest in the compendium is a document written by Harry Julius, whose father was the mine manager in the arsenic mining days.

The Minerama book title Cassiterite (1984) may be downloaded from here (doesn't work). See the part dealing with Emmaville in particular.

The Tin-Mining Industry in NSW 1911 by JE Carne (DIGS reference R00050677) was written near the end of the tin mining stage and has a good section on the Ottery Mine.

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Shoalhaven District Geology.

The Ottery Mine in 1922. From Grafton/Maclean mine data information

WEBB’S SILVER MINE NEAR EMMAVILLE, NSW AUSTRALIA

WEBB’S SILVER MINE NEAR EMMAVILLE 

NSW AUSTRALIA

Please take note: Practically all localities mentioned in these Blogs are on private property, under a mining lease or both. No-one should enter without permission from the landowner or lessee as appropriate.

The mine is marked "Silver" 7 (upper left)

I became aware of the existence of Webb’s Silver Mine (also known as Collison’s (NOT Collisions)) while I was still at school as a result of numerous visits to the late and much lamented Geological and Mining Museum in Sydney. This would have been in the mid 1950’s. The photos and specimens really piqued my interest in geology and mineralogy in particular.

It wasn’t until October 1988 that I made my one and only visit to the site when I rode my pushbike out there. The mine is reached by traveling 9-10 km after leaving The Gulf road, not far out of Emmaville, and then following a track to the right for a further 2.5 km. The mine site is usually described as being on Little Plant Creek, which runs into the Beardy River not far to the north. The map illustrated is the Grafton 1:250000 geological sheet.

My notes made that day mention a steel poppet head over a well-preserved shaft, numerous derelict sheds and ruins, 2X5 head stamper batteries, one in reasonable condition, piles of drill cores and specimens of galena, sphalerite and arsenopyrite on the dumps.

Photo by Wwoofa, Australian Lapidary Forum

Photo  by Wwoofa

Since then, several fossicking trips have be organised to Webb’s during the Emmaville Gemfest. The area is held under lease by Silver Mines Ltd; you can read their summary of the future prospects of the site here (now missing). I quote from this source: “Highest grade undeveloped silver project in Australia”, “a JORC compliant resource of over 12Moz of silver”, “From 1884 to1901 approximately 55,000t were mined at an average grade of at least 23oz/t”, “The current resources at a 70ppm Ag cut-off are approximately 1.49Mt @ 245ppm Ag, 0.27% Cu, 0.71% Pb and 1.56% Zn”.

The silver price is somewhat depressed at the moment (September 2014) which no doubt is quite depressing for the company, which is sitting on a great resource waiting for the right time to begin extracting it profitably.

Taken from Mole Tableland map DIGS R00041396

The classic reference to the geology of the Emmaville and Torrington areas is TWE David’s “Geology of the Vegetable Creek Tin-Mining Field”, 1887. (DIGS reference R00031676, if you wish to download a copy.) The relevant pages are 156/9. David tells us that the vein was discovered by Mr L Webb, that it can be traced for several miles, that the metalliferous part of the vein is nowhere more than 3 feet wide and that the ore minerals present are galena, copper pyrites, mispickel and “a variety of grey copper containing silver and a trace of gold (silver fahlerz)”. We know copper pyrites as chalcopyrite, mispickel as arsenopyrite and fahlerz as “fahlore”, a complex mineral of the tennantite-tetrahedrite family, containing at least 5 metals (iron, copper, zinc, silver and antimony) as well as arsenic and sulfur.

Another reference, written around the time when mining was at its peak, is “The Mineral Resources of NSW” (DIGS reference R00051137) compiled by EF Pittman in 1901. If you want to read what mining was like at that time, start at page 111. The photo of the mine is taken from this source. This is definitely a book that readers of this Blog should download.

From Pittman circa 1901

The comprehensive reference “The Mineral Deposits of NSW (Markham and Basden, 1975, DIGS Reference R00037944) has a lot of information on the mine, commencing on page 379 in the section dealing with the Mole Granite. We learn that the main shaft is 203m deep, with 7 major levels, that 3 separate ore shoots were mined, the main one yielding over 40 000t of ore containing 760-920 g/t of silver as well as significant quantities of the other metals.

The various documents available from the Web which have been uploaded by Silver Mines Ltd will give you a summary of their prospecting and that of their predecessors, which has been quite extensive since mining was active. Here are several:

From DIGS: Review of Environmental Factors (Exploration Activities at Webb’s Silver Mine) 2012 (R00070524). This is a report prepared by Geolink Pty Ltd for Silver Mines Ltd.

Report for Silver Mines Ltd 2010. Here. This is a good summary of the geology and potential of the mineral deposit.

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Shoalhaven District Geology.

JONES’ SWAMP CREEK – GUYRA TO INVERELL ROAD

JONES’ SWAMP CREEK – GUYRA  TO INVERELL ROAD

Over the years we’ve followed up suggestions, leads, hints – whatever you like to call them – about places where sapphires might be found. Jones’ Swamp (Creek or Gully) 3km north of Wandsworth on the Guyra to Inverell road was one of these. We only went once, because it was obvious that we had far better places to fossick than this. Nevertheless, it wasn’t a total failure and it would appear that there are still possibilities there.

The site is one of the original declared fossicking areas of the 1970’s, No. 39 to be exact. The place is on the left as you travel from Guyra and it is (surprise, surprise) basically a swamp. In 2003 that bothered me more than in later years; our experiences at

Rainy Swamp and Pretty Valley proved that sapphires are sometimes found in swamps.

Brett Brown visited the spot and we went out with him the following week. (Brett and Jenny used to run the Cathedral Gallery at White Cliffs).  Brett had found some typical sapphires and zircons, some of reasonable size, so it seemed promising.

As it turned out, the combination of swamp, winter and a shortage of water where it counted somewhat limited our fossicking, but I can confirm that there are gemstones there. We found no cutters, but that

Sue and Evelyn - and a nice fire for the day

doesn’t mean you won’t.

Here are some more pieces of information. According to Wwoofa (Australian Lapidary Forum thread on fossicking localities) the GPS co-ordinates are 6675680N 56356174E. There used to be a photograph there, but it’s been deleted to make more forum space. I don’t think it showed more than the bridge. Turn left at the bridge along a track. This is a broad travelling stock reserve, mostly barren granite country with swampy alluvium along the watercourse.

Two related reports concerning an Authority to Enter issued to Amsil Sapphires Pty Ltd in 1974 can be found in DIGS. The reference numbers are DIGS MR06260 and  MR06259 . Basically, the reports indicate that the creek does have good potential (see the extract) but you need to remember that this report is on another part of the creek. Furthermore, there might have been actual mining on that spot in the years after 1974.

Extract from Amsil Sapphires report

The map portion (from a map issued in 1972 with the Records of the Geological Survey of NSW, 14 part 1 – DIGS reference Records 14(1)), shows that basalt is widespread in the district (normal for sapphire deposits) with the country rock being granodiorite. It also reveals that both Moredun Creek (north) and Georges Creek (south) are sapphire bearing. You could try checking these localities in DIGS. Maps might also reveal other public access places along these three creeks worth investigating.

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Shoalhaven District Geology.

THE RED ROCK SAPPHIRE DEPOSIT NEAR WELLINGROVE, NEW ENGLAND DISTRICT NSW AUSTRALIA

THE RED ROCK SAPPHIRE DEPOSIT NEAR WELLINGROVE, NEW ENGLAND DISTRICT NSW AUSTRALIA

This is an unofficial name for a place that lies on a stock route north west of Glen Innes. It is accessed by a gate on the right hand side of the Bonshaw road (also known as Strathbogie and Wellingrove road) about 15km from Glen Innes. It is a km or 2 after the Reddestone Creek bridge, just before the road begins to descend to Back Plain Creek. There may or may not be a sign (reading Red Rock West) on the gate. Once through the gate, the location may be found by taking left hand branch tracks back towards the road. Total distance from the gate would be around 500 metres.

The gate, courtesy of Google Earth

Access is difficult when there is enough water to use for sieving (this is boggy country) and when access is easy the gully will probably be dry. This spot is at the head of a gully draining down to Back Plain Creek at the bottom of the hill. The country rock is basalt, often deeply weathered to a reddish soil loaded with ironstone nodules.

In the soil, scattered among the ironstone nodules, (which are the result of the weathering of the basalt) are small amounts of spinel, sapphire and zircon. How did they get here? This is not a normal alluvial deposit, of the sort we are familiar with in Yarrow Creek. It has some resemblance to 

Wellingrove Fossicking Area - "wash" at the bottom

the so-called “wash” at the Wellingrove Fossicking Area, which is 2-3 km away, as the crow flies. There, the overlying basalt ends at the point where the entry track leaves the sealed road. The underlying rock in the reserve is granite, which intrudes the Emmaville Volcanics on the northern edge. The “wash” may be thought of as a reworked volcanic ash layer, erupted before or along with the neighbouring basalt flow. There has been some concentration of the dense minerals, possibly by rain water at the time of the eruption, but there are few of the normal alluvial indicators such as pebbles of quartz which might have been expected to have been derived from the granite.

At Red Rock there may have been ash layers associated with the basalt, either below or between flows, which could be the source of the gems, or they may be derived from the basalt itself where they formed xenocrysts in the lava. See my blog on Dog’s Tooth Sapphires at Pretty Valley (here) for links to articles which throw some light on this subject.

Extract from the Grafton Metallogenic Map

The extract from the Grafton Metallogenic Map show the geology of the immediate area. The numbers refer to mineral localities. 1835 is the Wellingrove Fossicking Area, 1836 Pablo’s Sapphire Mine, 1837 an alluvial sapphire mine on Back Plain Creek, 1839 the Wellingrove limonite deposit and 1840 Hamel’s Gully, an alluvial deposit, probably on a former course of Reddestone Creek. Tb indicates “Tertiary basalt"). Note also the cross hatching, representing “alluvial” sapphire deposits. I’m only guessing, because I haven’t explored the area, that the prospect at Pablo’s Mine and the areas near it showing cross hatching (south of the Wellingrove Fossicking Area) are similar to Red Rock and that gems will be found near the edge of the basalt in other places in the area. None are likely to be productive enough to mine.

Minerama ran a field trip to Red Rock in 2003. Most people found a few colours but the lack of water was the real issue. I believe some cutters were found, however. Our fossicking group went there several times, with the same result – a few sapphires and zircons and a lot of mud and ironstone, enough to make it interesting even if we found no cutters.

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Shoalhaven District Geology.

THE CASCADES, YARROW CREEK NEAR GLEN INNES NSW AUSTRALIA

THE CASCADES, YARROW CREEK 

NEAR GLEN INNES NSW AUSTRALIA

The Crossing is in the centre, the long pool is on the left

This section of Yarrow Creek lies between Garnet Corner and The Crossing (click to go to the Blog List page for information on these locations). In dry weather, it is possible to park in the centre of the area, otherwise walking upstream from the crossing is the best option.

It can be divided into three parts. The uppermost is the cascade area itself. Immediately below Garnet Corner, the stream descends steeply through a drop of about 10 metres to a blockup of large granite boulders. There are numerous small pools and cracks on the way down. Some good gemstones have been extracted here using yabby

The beginning of the pool

pumps. However, a lot of sand has washed down from the Garnet Corner diggings as fossickers have dug and sieved over the years. This may have been washed further downstream by floods since the beginning of 2012.

Boulder blockup and the pool

No doubt there will be good finds made amongst the boulders one day, but it will take a lot of work to shift all but the smallest of them.

The middle section is a long

pool, commencing immediately below the boulders. Within 2 or 3 metres of the rocks, the water will be over your head. Good for swimming (brr) and perhaps ideal for a wetsuit and snorkel equipped fossicker. The 13 carat sapphire in the picture came from the edge of the deeper water. There are some large boulders in the pool immediately after the deepest part and then sand takes over. Some nice cutters have been found among the boulders.

Finds including the 13 carat stone

The final section leads to the rock barrier which crosses the creek another 100 metres or so further downstream. Wash is scarce along here but some good stones have come from the pool just above the barrier and by digging under the left bank (facing downstream).

There is an extensive alluvial flat on this bank which probably conceals former channels of the creek. Naturally, no-one knows where they are and they are probably loaded with gems.
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Song Studies. Bible studies based on hymns and songs

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Shoalhaven District Geology.

My finds at Minerama in 2007