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.

GEM DEPOSITS ALONG THE SARA RIVER, NEW ENGLAND NSW AUSTRALIA

GEM DEPOSITS ALONG THE SARA RIVER 

NEW ENGLAND NSW AUSTRALIA

This area is one of the most interesting gem producing regions in New South Wales. It’s also one of the most frustrating because of the difficulty in gaining access to the river and its tributaries. The map is extracted from 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, try Trove or locate DIGS.

Backwater-Kookabookra area, 40km south-east of Glen Innes

A further complication is that the river is sometimes called the Mitchell River; adding to the confusion is the fact that the nearby Mann River also has the Mitchell River as an alternative name!

There is plenty of information in issues of “Gold, Gem and Treasure” magazine, the Australian Lapidary Forum (ALF) website (here) and on DIGS (if you can locate it). 

Practically every tributary of the Sara (Mitchell) river is worth fossicking. Unfortunately, they are nearly all either on private land, in a National Park or simply nowhere near a road or track. If you wish to get onto private land areas, you are going to have to approach landowners for permission. Many of them will have already had enough of trespassers, shooters, people who dig holes and don’t backfill them, fire lighters and fence cutters, so be prepared for an earful.

It isn’t at all obvious from the map, but the river rises on the upper left of the map (west of Bullwarra), passes under the Backwater road (signposted as the Mitchell River) and flows south of Mt Mitchell via the Horse Shoe Bend to Kookabookra and beyond. The creek south of it is coloured green to indicate that it carries sapphire. The fact is, so do most of the streams and gullies on the map.

As a guide for readers, I’ll say something about the three areas I have actually been to. Firstly, upstream of the Backwater road bridge. We checked this out once for a possible Minerama trip but rejected it because of our poor finds that day. This was on Bullwarra property. The area was mined for gems, probably in the 1970’s, and all I found was a few bits of sapphire on the track (evidently spilled with gravel on the way to the treatment plant) and a nugget of cassiterite (tinstone) two or three centimetres across, which I saw lying on the ground. We were unaware of the fact that Cockatoo Creek was also gem bearing, otherwise we would have checked it out too.The presence of gold and cassiterite (tin) in the wash is normal for the area. Whether any mining was ever carried on in this creek I cannot say.

The Horse Shoe Bend section of the river is accessible by 4WD vehicles along the Horse Shoe Bend fire trail, which is reached by following McGarry’s Lane and Aqua Park Road eastwards off the Backwater road, a little south of the Yarrow Creek bridge. The descent is quite spectacular, with Crown Mountain (granite outcrops) straight ahead at the beginning of the trail. From the fossicking point of view, the problem is that most of the area is now in the Warra National Park. See this article from National Parks and Wildlife (here). Although much is said about the flora, fauna, history etc nothing is said about the reason many people would want to go there – fossicking. I have been there only once and found gold and small gemstones in the river easily enough. Another DIGS document (Reference number R00046781) makes for interesting reading at this stage. It’s a summary of the prospecting done in the area by Mr W Madgwick of Glen Innes in 1974. There is private property all around and trespassers are certainly not welcome.

Sara River at Kookabookra. Photo by Wwoofa, ALF

Most of the information available concerns the third area, at Kookabookra. This is well known as a fossicking area which produces quartz crystals, black tourmaline (schorl), gold, cassiterite (tin), topaz, sapphire and zircon. Fortunately for our generation, the early miners were only after gold and tin and discarded the rest. The actual area is well described in the blogs I listed near the beginning of this blog. This land is, I believe, a crown land lease held by the adjacent landowner who has given permission for fossickers to work there. Please respect this permission and do not trespass elsewhere, camp, light fires or leave rubbish behind. There is a further accessible area at the Sara River bridge a kilometre or so downstream, on the Ward’s Mistake road. This branches off the Pinkett road on the right a short distance back towards Glen Innes.

The Mitchell River Dredge from the Pinkett history book

This stretch of the river was extensively dredged, especially in the depression years. Sue’s grandfather worked as a woodcutter for the Mt Mitchell  (Mitchell River) dredge and her mother began her schooling at the nearby Kookabookra school. If you can find a copy, the little book “Pinkett, Mogg’s Swamp, Kookabookra Past and Present” (1988) makes good reading. 

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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 EBOR, NSW AUSTRALIA

SAPPHIRE DEPOSITS NEAR EBOR, NSW AUSTRALIA

Ebor is a small settlement on the eastern side of the New England Tableland. Its best known attractions are the Ebor Falls, where the river drops over a series of basalt flows, Cathedral Rocks National Park, Point Lookout (one of the most expansive views in Australia) and the Dutton Trout Hatchery, which you pass on the way to Point Lookout. Round Mountain is not only the highest point in New England, but you would have to travel several thousand kilometres northwards to find higher ground (Mt Bartle Frere, south of Cairns in north Queensland, in fact).

The sapphire deposits are located in places not far from the basalt margin (especially the outlying basalt on Round Mountain) and I would not be surprised if more remain to be discovered. The map adjoining is taken from “Records of the Geological Survey of NSW, 14 part 1” (1971). This includes an important article on Sapphires in the New England District. Ebor is on the extreme right of the included map. The DIGS reference is R00050764. The creeks highlighted in green are those known at the time to be gem bearing.

Apart from this map (which led me to check out the place) there are few other sources of information. There are several in the Dorrigo/Coffs Harbour Metallogenic Data notes and one in particular I found when searching DIGS – “V. Evans' Snowy Creek Sapphire Prospecting parish Rigney county Clarke, Ebor area” (DIGS reference R00039966).

Now, before you go rushing off in the hope of finding your fortune, take note of the fact that the areas mentioned are now in the Cathedral Rocks National Park where fossicking is not allowed. A reference about the park ( here) indicates the park boundaries and also that the remains of the sapphire prospecting are regarded as historic relics.

My own visits to the area included (a) Biscuit Creek at the top right of the map above (zero finds) (b) Native Dog Creek (black sand, probably ilmenite) (c) Boundary Creek, also top right of map

(black sand) and (d) Snowy Creek (the area highlighted in green on the map) (abundant black spinel).

This is a summary of the five areas indicated as gem bearing in the Metallogenic Mine Data (full title Metallogenic Study and Mineral Deposit Data Sheets Dorrigo - Coffs Harbour 1:250 000 Metallogenic Map (SH/5610, SH/5611) (explanatory notes)) The DIGS reference is R00037128.

Snowy Creek: described as a placer deposit carrying sapphire and topaz. “There is evidence of small-scale mining and fossicking activity along Snowy Creek upstream from its crossing by the Ebor-Guyra road. Position approximate. Not visited in the field."

Snowy Creek West: described as a sapphire alluvial placer.

Biscuit Creek: described as a placer deposit carrying sapphire and cassiterite, worked by dredging and/or sluicing.

Yooroonah (presumably near or in the Oaky River, south of the National Park): sapphire placer deposit worked by dredging and/or sluicing.

Oaky River, locality Yooroonah: sapphire and cassiterite placer worked by dredging and/or sluicing and by shallow pits.

This information is derived from the various reports concerning V Evans’ prospecting areas.

During 1978/79 attempts were made to have portion of Snowy Creek set apart as a fossicking area. Presumably this was in or near the land being prospected by Mr Evans. The land was subsequently incorporated in Cathedral Rocks National Park. Mr Evans prospected on both Biscuit Creek and Snowy Creek but no payable ground appears to have been located. The proposed fossicking area would have been on Snowy Creek.

The location of the various areas mentioned may be found on the map below, extracted from the Dorrigo/Coffs Harbour metallogenic map. It may take a little searching, but they are there!

418 – Biscuit Creek, 419 – Snowy Creek West, 422 - Snowy Creek, 667 and 669 – Oaky River/Yooroonah.

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Shoalhaven District Geology.

SCREW TIN – EMMAVILLE’S UNIQUE CASSITERITE FOSSILS

SCREW TIN – EMMAVILLE’S UNIQUE 

CASSITERITE FOSSILS

 

From the Mindat Entry on Doctor's Gully Emmaville

Marine fossils have been found in many places in NSW, of course – even in some of the ancient sedimentary rocks near Emmaville – but what makes the fossils described here unique is the fact that they are preserved in cassiterite (SnO₂). Generally speaking, most marine fossils are preserved as calcite or quartz or simply as impressions in what was once soft mud or sand. To the best of my knowledge, Emmaville is the only location where the replacing mineral is cassiterite.

This is a piece of information I’ve known about for many years, but I have no specimens of my own; however I have  found a photograph in the Mindat entry on Doctor’s Gully at Emmaville (here). There may be specimens in the Emmaville Mining Museum (there ought to be) and there probably are in museum and university collections elsewhere, but I don’t have access to these. From the photograph and the reports listed below you will see that the fossils are of two main types.

The first (the so-called screws) are segments of the stems of marine animals called crinoids. These are plentiful in sedimentary rocks ranging from the Silurian to the Permian period and are usually preserved in calcite . Crinoids resemble sea urchins and starfish; however they are attached to the sea floor by long stems made up of individual plates or ossicles. When seen from the edge, sections of these stems do resemble the thread of a screw or bolt, except that a little observation shows that that are not spirals, merely stacked discs. The miners who gave them their name probably weren’t fooled, but similar fossils in rocks have given rise to silly stories about ancient machines being found embedded in solid rock. 

The second type of fossil is of a small gastropod (snail) of a species commonly found in Permian sediments. Similar fossils (preserved in calcite) are common in Shoalhaven Group sediments at Gerroa on the south coast of NSW. Thus we have references to “screw tin” and “snail tin”. Here is a quote from the Wingham Chronicle and Manning Observer (Friday 9^th April 1937, page 1):

“Queerly shaped specimens which Emmaville miners have been finding in their claims, and which they have been calling "screw tin," and "snail tin" from the shape of the crystals, have been identified by Mr. T. Hodge-Smith, mineralogist at the Australian Museum as sea lilies and gastropods (star fish and sea snails) which countless thousands of years have turned into tin oxide. Such specimens have not been found anywhere else in the world, and prove that many thousands of years ago the sea swept over what is now the Tablelands.” Why this particular newspaper chose to report this information I can’t imagine. Did they issue a press release in 1937 after a field trip to investigate reports of cassiterite fossils being found near Emmaville?

The locality I’ve known about is Doctor’s Gully, an alluvial tin area near the Emmaville Golf Course (Gulf Road). However, it turns out that several other places nearby have also produced these fossils and there might have been others. It was just plain tin to the miners and worth money as such, so into the bags went beautiful specimens any of us would be proud to own. From the maps you can see that Doctor’s Gully has at least two tributaries gullies, called “Steele’s Gully” and “Charcoal Gully”. They are listed in the various reports as being 2km north of Emmaville. The Grafton-Maclean Mine Data sheets describe them as “fossil placers (fluvial)”. The Mine Data reference for all three is 1166. There is an additional reference (1266) to “Screw Tin Gully”, 3km north of Emmaville, described as “modern placer (fluvial)”. I can find no further reference to Screw Tin Gully but it is apparently in the same general area as the others.

Don’t imagine that you can just turn up at Emmaville and expect to find examples of these very special fossils. Read Jim Sharpe’s account of his experience in the Newsletter of the Mineralogical Society of NSW for November 2013 (here). Finally, a scholarly report on these fossils appeared in the Journal and Proceedings of The Royal Society of NSW for 1952. The article, by LJ Lawrence, may be downloaded here. It’s nearly at the end of the document and no plates have been reproduced. Note to the Royal Society: it’s time to make your records freely available in modern PDF format!

From Rasmus 1972. Check DIGS for the original

From the Grafton-Maclean Mine Data records

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Shoalhaven District Geology.