CASSITERITE CRYSTALS FROM ELSMORE HILL NEAR INVERELL NSW AUSTRALIA

CASSITERITE CRYSTALS FROM ELSMORE HILL NEAR INVERELL NSW AUSTRALIA

Photo from ALF

A recently reactivated thread on the Australian Lapidary Forum (ALF) about a well-known mineral hunting locality near Inverell, in the New England region of NSW Australia, should remind us all of how precarious our access to collecting localities really is. Read the thread here. Follow it and if a petition is commenced, be sure to add your name to it. It would be a good idea to get involved with the Forum if you aren’t already.

There is a wealth of information available on this locality. I’ve gathered together a number of photographs from some of these and assembled them, into a You Tube slide show, which you will find here. Not only is Elsmore the site of one of the earliest 

Photograph from Minerama book "Cassiterite"

payable alluvial tin deposits in Australia (1871), but it has (in more recent years) become the source of some of the most superb cassiterite crystal specimens in the world. A search on eBay will show that they are in great demand. Until recently, access to the fossicking spot had been made legally possible in an unusual way. The local Inverell Lapidary Club has held a mining lease over the area for the use of its members. By becoming a member of the Club, visitors could legally fossick there. I imagine that the revenue raised has been used to defray the cost of maintaining the mining lease.

What has caused the Club to surrender its lease I cannot say. It may be that income was falling behind expenses or perhaps that the Club has an aging membership (as many lapidary clubs do) and continuing to provide this service simply became a burden. It could be that changes in the mining law are making it difficult for smaller operators to stay in business. Whatever the reason, follow the ALF thread for more information.

Here are some useful references for you to follow up. As you read you will discover that cassiterite and quartz are only two of the many mineral species which have been found at Elsmore Hill.

The first few are to be found in the DIGS data base and can easily be downloaded. The most comprehensive reference is: Geological Survey Report 45 (1966): The Geology and Tin Deposits of the Elsmore Area. The DIGS reference is R00050621. Related to this document, and incorporating much of it, is Elsmore Tin Mine, Inverell which incorporated material from mine records 1934-1981 (DIGS R00046476).

Diggings on the lease

You will discover that the basic geology consists of granite intruding Palaeozoic sediments, overlain by Tertiary basalt. The primary cassiterite deposits are associated with the granite intrusion. Secondary deposits include modern alluvial material and, in particular, “deep leads” – older alluvial material lying beneath the basalt. Much of the prospecting in the area has been (and still is) directed to locating payable wash in these concealed leads. The classic geological map is “Geological Map of the Tin-bearing district around Tingha, Stannifer and Elsmore” by Carne and Pittman (1910). (DIGS R00030525). There is a lot more recent material available also (Inverell metallogenic study) but these should help you to understand what the place is all about.

A search through DIGS shows that there many other reports available from this source. One is Partial relinquishment report EL7177 Elsmore 2011 Malachite Resources (DIGS RE0001817), which is quite recent. The article in Mindat includes further photographs, mineral lists and references here.

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Shoalhaven District Geology.

Tin Sluicing at Elsmore

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.

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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All New England and other Geology blogs and videos

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Limestone Caves of NSW

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Song Studies. Bible studies based on hymns and songs

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Shoalhaven District Geology.