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Saturday, 20 December 2014

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 2nd 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 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

My gem hunting/mining You Tube playlist may be found here. I have 3 other playlists - 

the Blue Mountains, Glen Innes and New Zealand.

Thursday, 11 December 2014

THE EMERALD MINE NEAR EMMAVILLE


The Emerald Mine (before 1900)
Any book produced for “rockhounds” in Australia (from the 1950’s on) will mention The Emerald Mine, such is the fascination of this beautiful gem.
I have several in front of me as I write. The first is The Australian Gemhunter’s Guide by KJ Buchester (1965).Writing of Australian emerald deposits, he says “The New South Wales deposit was the first to be discovered, in 1890, at a site about 6 miles north-north-east of Emmaville, a small town 24 miles north-east of Inverell. This location, known as de Milhou’s Reef, had originally been mined for tin, and emeralds were later observed in the old mine dump.
Thereupon a company was formed to follow up the emerald bearing veins.” Buchester then gives some production figures and recounts some of the problems encountered by the miners. He also mentions a specimen in the Australian Museum, no doubt one of those which excited me when I was a teenager.
Later in the book he mentions that the mine was probably under lease and that emerald, beryl, topaz, quartz crystal and fluorspar could be found there.
The second book is “Australian and New Zealand Gemstones”, edited by Bill Myatt (1972). He writes “Near Emmaville in northern New South Wales active mining was carried out in the latter half of the last century. The gem was extracted from a pegmatite dyke and occurred in association with cassiterite and topaz.”
Now all this information is true, but if you are longing to get at those dumps, take note of the fact that most of this material has since been pushed back into the old shafts and access to the public is strictly prohibited. It may be possible to go there with an organised group during Emmaville’s biannual Gemfest, but even that is unlikely. If you want more specialised information on the locality, get hold of a copy of the 1993 Minerama book, “Beryl” from the Aussie Sapphire website (here). If you aren’t a member of the Australian Lapidary Forum (ALF), this would be a good time to explore the site (here).
The photographs on the right were taken in July 1993 as we were preparing field trips for Minerama that year.
Diagrams from David's report
DA Porter on his rounds
TWE David, in the process of becoming Australia’s best-known geologist at the time, reported on the finding of emeralds near Emmaville in the Annual Report of the NSW Department of Mines for 1891 (DIGS Reference R0001418). The report is found from pages 229-234 and is very thorough, in typical TWED style. The  Sydney Morning Herald commented on David’s findings (here). In almost any reference you consult, Mr DA Porter of Tamworth is given credit for the discovery of emeralds at de Milhou’s Reef. He himself downplayed his part in a letter to the Editor of the Herald 2 days later (here), naming Mr AB Butler of Port Macquarie as the true discoverer. History has not been as kind to Butler as it has to Porter and I haven’t found out anything else about him (yet). Donald Alexander Porter was an inspector of school buildings in northern NSW and travelled extensively through the very active mining regions of his day. He not only collected many fine mineral specimens but also had a number of papers published in the Journal of the Royal Society of NSW. A lot of the specimens he collected are now in the collection of the Australian Museum in Sydney, perhaps including the one illustrated. My thanks to the publishers of the Australian Journal of Mineralogy, Volume 4 No. 2 for some of this information and the photographs of Porter and the museum specimen.

There is a lot of information freely available about this particular mine and you can use the resources given in the Blog entry on Reid’s Copper Mine as a guide. An important source of information is the report by Wynn and Loudon (1966) titled “The Emerald and Associated Mines”. The DIGS reference is R0005608. Unfortunately, my copy has been missing for years, suspected of being retained by one of my Moss Vale High School students. The copy you will download from DIGS is missing the maps and sections, showing what a popular location the Emerald Mine has been! Fortunately, I have a copy of these in PDF format and the illustrations at the end of the Blog come from this. I hope you can read it. You can enlarge them.
If you are in Emmaville, make a point of visiting the Mining Museum (here). As well as specimens from this particular mine, there are many other fine minerals to be seen. See also this article from Geohavens (here) for further information on Australian emeralds. 
You will find my You Tube playlist on gemstones and mining here. I have three other playlists - on the Blue Mountains, Glen Innes and New Zealand.
The missing illustrations from Wynn and Loudon's report