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Wednesday 11 October 2017

THE GRAFTON-MACLEAN METALLOGENIC MAP

The NSW Geological Survey has compiled an extensive series of reports which can be used to assist in the search for new mineral deposits or simply to locate existing ones. The Grafton-Maclean Metallogenic Map group of documents may be downloaded from DIGS (here) using this reference number: R00056102. The files take up about 65 MB and consist of many related documents apart from the map itself. These represent the original report broken up into sections.
The map includes the Torrington and Emmaville districts and extends southwards to Glencoe. The western edge of the sheet joins the Inverell map, and it extends to the coast in the east. The Inverell map will be the subject of a later blog.
The map provides a vast amount of information – geology, structure and mineral deposits as well as the underlying topography, roads, watercourses etc. This can make locating something quite difficult and frustrating, so it’s important to become familiar with the meaning of the colours and symbols provided around the margins of the map. Here is an example of what the map contains:

The rest of the documents in the downloaded folder provide information on the background geology and the individual mineral deposits. Take, for example the deposit number 1837, roughly in the centre of the extract. The table of mineral deposits (left of map) describes this as “Back Plain Creek sapphire (Zr)”.
You will find the deposit listed in the file titled “Text_4.3MB_zip_of_4_deposit;_pdf” (the first of four of these). When the file is open, scan through until you come to “GR 1837”, which is the extract below.
More information can be found by looking up the Mineral Occurrence List in the second part of the above file, using the same deposit number (1837).
 You could expand your knowledge of the area by searching other deposit numbers nearby, whether you can find them on the map or not.
Another possibilty is to search the Mindat data base (here) using the mine name. This is what you will find for Back Plain Creek:
Located approximately 15kms NNW of Glen Innes.
Operated as a small open cut and shallow pits 1971 to 1990s.
Mineral List
2 entries listed. 1 valid mineral.
The above list contains all mineral locality references listed on mindat.org. This does not claim to be a complete list. If you know of more minerals from this site, please register so you can add to our database. This locality information is for reference purposes only. You should never attempt to visit any sites listed in mindat.org without first ensuring that you have the permission of the land and/or mineral rights holders for access and that you are aware of all safety precautions necessary.

References
Metallogenic Study and Mineral Deposit Data Sheets: Grafton-Maclean Metallogenic Map (SH/56-6, SH/56-7), Geological Survey of New South Wales, 2001: HF Henley, RE Brown, JW Brownlow, RG Barnes and WJ Stroud. Published by the Geological Survey of New South Wales.

Finally, you might like to check out my blog on the Back Plain Creek area here.
Here is a link to a slide show of pictures from the data package: here.

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