ALLUVIAL DIAMOND MINING IN THE NEW ENGLAND REGION OF NSW AUSTRALIA

ALLUVIAL DIAMOND MINING IN THE NEW ENGLAND REGION OF NSW AUSTRALIA

 

Most gem hunters seem to be unaware that diamonds have been mined in NSW (off and on) since the gold rush days in the middle of the 19^th century. The list of places where at least one diamond has been found is very extensive and I suspect that it would be much longer if the old time miners had not suffered from tunnel vision. “If it’s not gold (or tin) we’re not interested in it. Chuck it out.”

Only at Bingara and Copeton (formerly called Boggy Camp, south of Inverell) were the workings extensive and even then they could hardly have been very profitable. Both places were being prospected for gold or tin when “these funny looking stones” turned up. Sufficient curiosity was aroused for specimens to be sent off for identification and minor rushes followed.

Subsequent searches for primary deposits (like those now being mined in Western Australia) have not met with much success, despite the fact that the diamonds had to reach the Earth’s surface somewhere. From the gem hunting point of view, this is probably a good thing, as modern diamond mining is very big business and casual fossickers are most unwelcome in the vicinity.

Your only real source of accurate information is in the records of the Geological Survey and the Mines Department of NSW. I have mentioned DIGS on numerous occasions, but it is a website that anyone with an interest in things geological needs to get to know. You will have to search Google to locate it. Make sure you bookmark it or put it into your Favourites, if that’s what your web browser does. Click on “Search DIGS” enter “diamond” in the Subject Terms/Keyword box, press “Search” and you will be confronted with a list of 1000 records.  If this seems somewhat overwhelming, try putting in a locality (eg Copeton). This reduces the 1000 to 94, a much more manageable number if you want to start researching. It’s a series of logical steps to bring up a document on your screen, where you can read it, save it or delete it as you please. Note the size of the document before you commit yourself to waiting for it for maybe half an hour.

If you want a short cut to a few interesting documents, just copy these numbers into the second box at the top of the initial search box.

R00003264 will take you to the Annual Report of the D of M for 1900. Notes on diamond mining for that year are on pages 60/61 of the report.

R00050830 takes you to the document “Industry 18: Mineral Industry NSW - 1980 - Gemstones 2nd Edition”. The section dealing with diamonds is on pages 32/67.

R00047949 brings up the most comprehensive document of them all – “Diamonds in NSW”, from which much of the previous document has been taken.

So you want to go and look for diamonds yourself? The references above will give you lots of clues to locations, nearly all of which will turn out to be privately owned. Make sure you get permission before entering any private property and respect the wishes of all landowners.

Staggy Creek on the Copeton Dam road near Inverell is the only place that seems to be easily accessible to the public. Google Staggy Creek fossicking and you will find lots of web pages to explore. Some of them even mention finding diamonds there! Check out my entry in myBlog as well. You can always go and look at the specimens at the Inverell Tourist Information Centre if you want to compare your finds with the real thing.

The illustrations accompanying this blog were adapted from the above references and similar ones found on DIGS.

I also recommend you check out my video on the subject, which does not include any footage of actual fossicking but does reproduce these illustrations and other similar ones. The link is here.

Addition 27/06/2015. I came across this interesting ebook today. It's called Sydney and the Cudgegong Diamond Fields, written in 1870 by Angus Mackay, MLA. It describes a journey from Melbourne to Sydney by ship, then by train to Bowenfels (the end of the line in 1870) and on via Mudgee to the Cudgegong River, where diamonds had been discovered not long before. It really does give a great insight into the conditions of the times. Download from Trove here.

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Shoalhaven District Geology.

THE RUBY HILL GARNET DEPOSIT NEAR BINGARA, NEW ENGLAND NSW AUSTRALIA

THE RUBY HILL GARNET DEPOSIT NEAR BINGARA, NEW ENGLAND NSW AUSTRALIA

Google Earth photo - the signpost coming from the north

I’ve passed by this place several times without going in. As there are many references to it as a fossicking area, I suppose it must be open to the public, though whether this is public or private land I’m unable to say. It is well signposted, more visibly so when travelling south from Bingara, being on the right hand side of the road linking Bingara to Barraba (commonly called the Fossickers Way). The most precise distance from Bingara I’ve read is 18.6km, though from what point in the town this was measured is not stated. There are no rubies there – they proved to be garnets – but there have been several dubious claims of diamonds being found there. More of this later.

The earliest reference to the place appears to be DA Porter, “Notes on Some Minerals and Mineral Locations in the Northern Districts of NSW”, published in the Journal of the Royal Society of NSW in 1894. I read this many years ago and there is no certainty that Porter is referring to the present day Ruby Hill. The next reference is by JM Curran, in the same Journal in 1896. JF Lovering quotes Curran as saying that a red, pyrope-rich garnet was found in a coarsely-crystallising basic rock within the basalt at Ruby Hill. The easiest reference to read from the early days is in “The Mineral Resources of NSW”, by EF Pittman, 1901. Search Trove.

Photo from Pittman, 1901

Pittman wrote as follows: “A small hill, about eighty feet in height, which is intersected by several basalt dykes, was pegged out some years ago by a miner named Butt, who was attracted by some red crystals in the basalt. Under the impression that these crystals were rubies, Butt drove a tunnel, forty feet in length, in one of the hard basalt dykes, and only desisted on being informed that the red stones were garnets and of no value.” Pittman went on to tell of the search for diamonds on the same hill. He gives the date 1889 for the formation of a diamond prospecting syndicate. The upshot of this was that “Ten diamonds, weighing in the aggregate four and one-eighth carats, were obtained from it. The diamonds were remarkable in that they each had a distinct depression or pitting on one of the faces.”

The first edition of “Gemstones”, Mineral Industry series 18, page 66, (1960) (DIGS reference R00050829) throws doubt on the validity of this discovery; however it also states that “in 1922 ER Dickens treated alluvial material in the vicinity of Ruby Hill, and it is reported that some hundreds of small diamonds were obtained but were not sold”. I wonder what became of them? There are other Ruby Hills in NSW so perhaps these diamonds came from elsewhere. The second edition (1980, DIGS reference R00050830) mentions only the earlier find.

Map from Pittman, 1901

What emerges from these readings is that the garnets were found both in the breccia, which makes up much of the hill, and in the dykes which intrude it. They are apparently derived from fragments of eclogite found in the breccia (along with many other types of rock, which is typical of brecciated volcanic pipes) and in the later basalt, which they could have entered from the breccia when it was intruded by the basaltic magma. They might also have been carried up from a considerable depth from the same source rock as that penetrated by the breccia.

Lovering addressed the nature of the eclogite fragments in an article in the Journal of the Royal Society of NSW in 1964 (Volume 97, pages 73-79). He stated “Eclogites occurring as inclusions in igneous pipes are particularly important in that they may well represent direct samples of the upper mantle caught up in the magma of the pipe during its passage to the earth’s surface”. He prefers to call the inclusions “garnet granulite” and adds that individual xenocrysts of garnet are also found in the breccia and dykes, no doubt derived from the breakdown of the granulite.

Because of the (apparently) superficial resemblance of the occurrence to South African diamond bearing kimberlite pipes, there has been quite a lot of interest in this locality as a potential source of diamonds.  One such report, written by GL Rolfe for Anaconda Australia Inc. in 1979 (DIGS reference R00015604), concluded that the rocks there were unlikely to be diamantiferous. Commenting on the garnets, the report states “The most common xenocryst in both the breccia and basalt is garnet. The garnets are generally orange pink in colour, size varies from 1 to 5mm. Reaction of the garnet with the magma during ascent to the surface has resulted in kelyphitic rims one to two mm wide. The keliphytic rims consist of clay mineral and zeolites. The rims are wider in the basalt than the breccia, indicating a longer period of disequilibrium between the garnet and magma”.

Reports from fossickers of outings to Ruby Hill are few. Some say they found little or nothing, others that there were numerous small garnets in the soil. Obviously, the soil derived from the dykes is going to be the most productive, so these places need to be identified from the map, rather than by digging at random. It seems that nearly all the gems will be found in a small sized mesh sieve, a coarser sieve being used to remove larger pieces of rock etc. There will probably be no water on site, so dry sieving to concentrate the gems followed by a dip in water you will need to take with you is the most likely approach. There may be water in nearby Hall’s Creek, but this will almost certainly be on private property.

Another useful reference:  A thread from Prospecting Australia’s website (here). There are some interesting photographs in this thread, but as there is no mention of sapphire being found at Ruby Hill in any other reference, the bluish stones may have come from somewhere else. Some object for scale (such as a coin) in the photos would have helped.

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Shoalhaven District Geology.

SAPPHIRE DEPOSITS AT BACK PLAIN NEAR GLEN INNES NSW AUSTRALIA

SAPPHIRE DEPOSITS AT BACK PLAIN 

NEAR GLEN INNES NSW AUSTRALIA

Before you read this blog, I recommend that you read my blog entry “The Red Rock Sapphire Deposit” (here). It deals with gemstone deposits in the same general area as I am covering here.

A good starting point in understanding the sapphire deposits at Back Plain (not Back Plains, by the way) is the map at the back of “Records of the Geological Survey of NSW, 14 Part 1 (1971)”, DIGS reference R00050764. If you haven’t downloaded this document yet, you should do so. The map shows only that Wellingrove Creek (left) and the Wellingrove Fossicking Area (on the letters Pgw)) are sources of sapphire. Both are marked in green. The reddish area near the centre of the map (marked Ts) is apparently an area of Tertiary sediments associated with the basalt.

The next map is extracted from the “Quarterly Notes of the Geological Survey of NSW 103, April 1997” (page 13). The DIGS Reference is R00040935. My extract from the map shows the following sapphire bearing areas of interest to us here: Back Plain Creek in the centre, with a tributary to the west of it and the creek flowing down from the Wellingrove Fossicking Area into Wellingrove Creek.

The third map has been extracted from the Grafton-Maclean Metallogenic Map (DIGS reference R00056102).  To help you align it with the other maps, the Wellingrove Fossicking Area is approximately in the centre, shown as 1835. 1836 is identified in the accompanying notes as Pablos Mine and 1837 as the Back Plain Creek deposit, elsewhere called the Truro Mine. We can distinguish two types of sapphire deposits on this map. Firstly, the close cross hatched areas (Wellingrove Creek, the stream draining the Wellingrove Fossicking Area and Back Plain Creek, not named on the map) which are regular alluvial deposits, and secondly, the broad hatched areas (one around Pablos Mine and the other near the top of the map adjoining an area of Tertiary basalt labelled Tb. These are locations where spinel, sapphire and zircon are to be found in the soil, possibly derived from tuffaceous sediments intercalated with the earliest basalt flows. The Red Rock deposit (see above) is like that and the Wellingrove Fossicking Area deposit could be a contemporaneous alluvial concentration derived from such sediments.

There isn’t much information available about these deposits, except for one (Truro) and even that isn’t clear

Ruwenzorie Road turnoff (on right)

cut. Starting from the north, we have a site which has at least the potential to produce some gems. This is the area shown in broad hatching along Ruwenzorie Road, which branches off to the right (north) from the Strathbogie Road. This is before you come to the back road from Wellingrove (Polhill Road). This road crosses Back Plain Creek after 2.5km at a place where there are some rocky outcrops. I only went there once and found some colour easily enough (without getting wet or covered with leaches). It’s certainly worth a try, if it’s still accessible. Then there is the possibility of gems in the soil on the road side. You could try dry sieving and then take the concentrate to Back Plain Creek to see what’s in it.

Pablos Mine location (from Mindat)

Pablos Mine appears to be on a tributary of Back Plain Creek south of the Wellingrove Fossicking Area. All I can find from the metallogenic notes is that it was worked by Pablos Mining (1970-73) by shallow pits or scrapings. It’s described as a “modern placer (fluvial)”.

The problem starts with the Back Plain Mine. The metallogenic notes contain quite a bit of information – worked by SC Burgis (1971), Pablos Mining (1970-73) and Nunan Pty Ltd circa 1990. “This deposit comprises high grade sapphires and abundant zircon. The headwaters of the creek drain from a red soil 

Back Plain Mine location (from Mindat)

plateau where the deposits were quite rich. The abundant zircon contrasts strongly with Reddestone Creek immediately to the east where zircon is relatively minor. Alluvial placer”. The difficulty arises when you look at the Mindat information for the Back Plain Mine (here). It is clearly identified as the Back Plain Mine (Truro). This would be fine, except that we have a lot of information about the Truro Mine from the NSW Department of Minerals and Energy publication Minfo 27 (1990) which deals with the opening of the mine belonging to TJ and PV Nunan Pty Ltd. You can download the document from DIGS, reference number R00040997. The included map shows that the mine was on the right hand 

Truro Mine location (from Minfo 27)

side of the Strathbogie Road, past the Wellingrove turnoff. This is several kilometres from the indicated site of the Back Plain Mine. Perhaps the wash from the Back Plain Mine was trucked to Truro Mine for treatment. That there was a mine near Truro homestead is beyond doubt. You could see the activity from the Strathbogie Road, but when it closed down I can’t say.

My thanks go to the NSW Geological Survey, Mindat and Google Maps for information and illustrations used in this blog. Without these it would be difficult to make sense of this interesting area.

To explore the satellite images better, I suggest a Google search for "Mindat Pablos Mine NSW" and "Mindat Back Plain Mine NSW". You can then follow the "Maps" link, "Maps Pages" and select "satellite"to get to the images shown above.

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Shoalhaven District Geology.

SAPPHIRE DEPOSITS NEAR THE GWYDIR HIGHWAY EAST OF GLEN INNES

SAPPHIRE DEPOSITS NEAR THE GWYDIR HIGHWAY EAST OF GLEN INNES

Dirty Creek is in the centre of the map (from DIGS R00050764)

When I first moved to Glen Innes in 1988 I had with me a copy of the Records of the Geological Survey of NSW 14(1), which contains a valuable article titled “Sapphires in the New England District, New South Wales”. If you would like to download a copy, the DIGS reference is R00050764. The map at the end of the document is a useful tool for locating interesting fossicking spots. I need to point out, however, that, apart from Yarrow Creek, some of our best sites (eg Pretty Valley, Rainy Swamp, Back Creek and Frenchies Swamp Creek) are not indicated as sapphire bearing at all. The map in Mineral Industry 18 Gemstones 2^nd Edition (1980) DIGS reference R00050830, is based on the earlier one.

Dirty Creek 1652 Tarcoodie 1704 (from metallogenic map)

One place seemed to be remote from all the others and that is Dirty Creek, near the Glen Elgin road turnoff from the Gwydir Highway about 30km east of Glen Innes. See the map extracts for guidance, also Google Earth. I now know that there are gemstones to be found in many creeks in the Glen Elgin area but it isn’t an area I’ve looked at very closely. Dirty Creek is crossed by the Glen Elgin road immediately after the turnoff from the highway. After a few hundred metres, the creek joins the Rocky River almost at the highway bridge. The Rocky River is known as the Timbarra River further downstream.

Please note that anything I say about access may no longer be true. Under no circumstances should you enter private land without permission.

Stock reserve gate

There is some kind of stock reserve covering the lower parts of Dirty Creek. About 300 or so metres before the Glen Elgin turnoff there is a gate opening into the reserve on the northern side of the highway. The creek runs through swampy and sandy country and you wouldn’t expect to find much in it. All I ever turned up were a few very waterworn sapphire and zircon fragments as well as black spinel and tourmaline. These were more abundant downstream where there are granite outcrops. Upstream you come to the boundary fence. Note that the area shown on the Grafton-Maclean metallogenic map as being the site of mining activity is a km or so upstream. Dirty Creek is shown as deposit number 1652

I haven’t examined Dirty Creek between the Glen Elgin bridge and the junction with Rocky River, but there are many granite outcrops in this stretch so there could be some gemstone concentrations waiting there for those who don’t mind getting wet.

Rocky River reserve entrance

Immediately after the highway bridge there is a track on the northern side entering what appears to be another reserve, through which the river flows. A lot of fossicking has been done here because there is usually a good flow of water and there is a lot of gravel in the river and its banks. I’ve only washed a casual sieve or two, but they always contained some gem material. It’s my guess that this has come down Dirty Creek and into the Rocky as I could find nothing upstream of the Rocky River bridge, though the usual problems of swampy ground and access to the river make this statement difficult to confirm.

The third gem bearing spot in the area is Tarcoodie, which I have not been able to locate, though the mine data information suggests that quite a bit work was done on the deposit. It is shown as deposit number 1704 and ought to be on the southern side of the road in the vicinity of the prison farm (afforestation camp). Stay out of that area!

Extracts from Grafton-Maclean Metallogenic Data

GR1652 (YJ0011) G Dirty Creek OCC sapphire modern placer (fluvial)

NAME(S): Dirty Creek Recorder(s): K. Ringwood, 24/11/1995

LOCATION Map sheets: SH/56-6, 9338-IV-S Coordinates (MGAz56): 404206mE, 6721488mN Locality: 29 km ENE of Glen Innes

Location method: 25K topo map Co: Clive Ph: Lewis Por: 42, 43, 45

MINING HISTORY Workings: dredging or sluicing Extent (m): d: l: 2000 w:

Prods and period:

Exploration:

HOST ROCK(S): clastic sediment, alluvium, Quaternary

DEPOSIT CHARACTER Ore minerals: (sapphire) Alteration:

Gangue: Production: Resources:

Ore genesis: modern placer (fluvial) Relation to host: stratiform Orientation:

REMARKS:

REFERENCES: MacNevin (1972), MacNevin & Holmes (1980)

GR1704 (YJ0010) G Tarcoodie deposit OCC sapphire modern placer (fluvial)

NAME(S): Tarcoodie deposit Recorder(s): H F Henley, 7/2/1992 & 24/11/1995

LOCATION Map sheets: SH/56-6, 9338-IV-S Coordinates (MGAz56): 409405mE, 6720368mN Locality: 36 km E of Glen Innes

Location method: 25K topo map Co: Clive Ph: Mount Mitchell Por: 21, 22; PMA

MINING HISTORY Workings: dredging or sluicing Extent (m): d: l: w:

Prods and period: Gem Exploration (July 1971 - March 1972)

Exploration: G and J Gems P/L (1988-present)

HOST ROCK(S): felsic intrusive, granite, Quaternary sediments, alluvial plain, Quaternary

DEPOSIT CHARACTER Ore minerals: (sapphire) Alteration:

Gangue: Production: Resources:

Ore genesis: modern placer (fluvial) Relation to host: stratiform Orientation:

REMARKS: substantial conventional production plant type

REFERENCES: GS1990/226

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Shoalhaven District Geology.