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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

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