John's New England Minerals and General Geology Blog: arsenopyrite

Thursday, 31 December 2015

GADEN’S LODE GULF ROAD, EMMAVILLE

GADEN’S LODE GULF ROAD, EMMAVILLE

This is another old mining area I haven’t visited, or if I have I didn’t know its name and it has faded from memory. There are quite a few mineral deposits in the area, of which Gaden’s appears to be the best known. It has been the site of several Emmaville Gemfest field trips and I am indebted to Jewellery Pirate for information and photographs from his Blog.

If you examine the satellite image from Google Earth you will see the site of Gaden’s Lode marked in pink in the centre (source: Mindat). The most notable feature on the image is the joint pattern in the Mole Granite which occupies a broad swathe of country across the centre. Observe how these joints disappear around Torrington/Torrington State Forest where the granite is still covered by part of its original “roof”. This is the Torrington Pendant of older sedimentary rocks. The joints have controlled the deposition of ore bodies both in the granite and in the adjacent areas where the granite is still concealed by these older rocks.

The map was extracted from the Grafton-Maclean Metallogenic Map; the numbers locate the various mines and prospects. I know that some of the numbers are hard to read and I can’t interpret them all, but here is a list of those I can (lowest to highest) with some information (from Mindat) about each, where there is any. The names in brackets are alternative names or nearby mines/prospects.

0300 Chinaman’s Gully Sn vein (Murphys lode; Suicide tunnel). Operated as underground workings, adits, shafts and shallow pits. Production from 1878 to 1965. Chinaman’s Gully alluvials: Dredging operations until the late 1960s.

0312 Gaden’s Lode Sn W Cu U monazite vein (Gaydens lode; Garths lode; Garths wolfram lode; Garths uranium lode). Operated as underground workings, open cut, shafts, adits and shallow pits from 1877 to the late 1960s.

0313 Stormer’s Lode Sn fluorite Cu U vein (Garths lode; Garths wolfram mine; Garths uranium mine; Gadens uranium mine; Gadens lode; Gaydens lode; Gardens lode). Operated as shallow pits, open cut, shafts and adits 1913 to 1954.

0314 Garth’s Lode Sn vein.

0315 Heiser’s Lode U Sn vein (Garths lode; Fish & Chips). Operated as shafts and pits 1877 to 1968.

0330 Stevens and Charlton vein Sn W (Stormers reef). Operated as shafts and shallow pits 1887 to 1970.

0331 Mineral Tunnel Sn As Zn Pb vein. Operated as adits, shafts and open cut 1889 to 1893. Also alluvials.

0332 Suicide Tunnel Sn vein. Operated as underground workings, shaft and shallow pits 1889 to 1893. Located slightly West of Mineral Tunnel workings.

0329 McKinnon’s Reef vein Sn W As Cu Bi (Paradise lodes; Blue lode; Murphys lode; Garths tin lode; Mineral lode). Operated as underground workings, open cut, shafts, adits and shallow pits 1878 to 1950.

0754 Small prospect Sn vein.

0755 Mineral tunnel alluvials Sn placer.

0757 Minor Lode Sn vein.

0758 Hill Crest deposit beryl pegmatite. Operated as shafts from 1890 to 1890. (This may be a wrong identification)

Ore minerals in Gaden's Mine (photo Jewellery Pirate)

There are three principal types of ore bodies in the area: tin (Sn) veins, which consist largely of quartz and cassiterite, polymetallic veins which contain a wide variety of sulphides such as pyrite, chalcopyrite and arsenopyrite as well as cassiterite and wolframite, and pegmatites, which frequently contain fluorite, topaz, tourmaline and beryl as well as some of the ore minerals already mentioned. All types occur in this location.

Where is this mineral collectors’ paradise? You are 60 years late for the easy pickings, but if you are diligent in searching out the locations listed above (not forgetting the alluvial deposits) you are sure to find something of interest.

The area lies between Flagstone and Paradise Creeks. Proceed along the Gulf Road from Emmaville. A useful reference is Geo-Log 2011 – a publication by the Amateur Geological Society of the Hunter Valley, beginning on page 42 (here). (missing - try searching for it on Google).The whole publication is worth reading, as are the other Geo-Logs in the series.

Dump at Gaden's Mine

The track to Gaden’s branches off to the right just after the Torrington State Conservation Area is reached. This is after you have crossed Flagstone Creek. Naturally the track condition is going to vary according to weather conditions but it’s unlikely to be drivable by 2 WD vehicles. Searching DIGS (if you can find it) will produce many reports on the area which are easily downloaded.

Of special interest are the references to radioactive minerals from some of these mines

and prospects.. During and after World War 11 there was a lot of prospecting for uranium minerals in particular when it was commonly believed that the world would soon be using nuclear energy as its major power source, as well as for making nuclear weapons. (The extensive uranium deposits in the Northern Territory and South Australia had not then been discovered.) The publication “Radioactive Prospects in NSW” (here) dates from this time. It should be noted that monazite, which contains the radioactive metal thorium, is also found in this area.

https://johnsbluemountainsblog.blogspot.com/2013/12/links-to-all-blog-entries-and-relevant.html All Blue Mountains blogs and videos

https://johnsnewenglandminerals.blogspot.com/2013/12/list-of-all-blog-entries-to-date.html

All New England and other Geology blogs and videos

https://www.blogger.com/blog/posts/1325599670344725659?pli=1

Limestone Caves of NSW

https://www.blogger.com/blog/post/edit/1147003616874115974/2430103125095714141

Song Studies. Bible studies based on hymns and songs

https://www.blogger.com/blog/posts/1515863000684737715

Shoalhaven District Geology.

Sunday, 28 September 2014

THE OTTERY MINE, TENT HILL NEAR EMMAVILLE NSW AUSTRALIA

THE OTTERY MINE, TENT HILL NEAR EMMAVILLE

NSW AUSTRALIA

The site in December 1967

The Ottery Mine is one of the few places in NSW where the public can go and get a good idea of what went on at a mine in “the good old days”. Usually, such sites are out of bounds, being on current mining leases or private land or considered too dangerous to allow people in. The Ottery is different – a lot of money has been spent to make the old mine site accessible and provide good information so you can see for yourself how it all came together.

The mine is close to the Tent Hill-Torrington road just a few km from the old tin mining town of Emmaville, itself about 40km from Glen Innes. For more information on how to get there and what there is to see, I recommend the following websites: Aussietowns – Emmaville (here), the Northern NSW site (here) and Aussie Sapphire’s Blog (here).

The site in May 1991

Before I move on to more technical stuff, here are few personal observations which might enhance your visit.

I first saw this place in December 1967. The main features haven’t changed greatly since then – the chimney, the condensing chambers, the damaged environment (though this has been improved a lot by the mine site rehabilitation that has gone on since then.) In 1988 I collected specimens of pyrite and arsenopyrite there. You can still smell the sulphurous odour around the site. I observed (on the right near the car park) that there were a number of decaying wooden barrels which still contained a whitish substance. Maybe they are still there and perhaps it is refined arsenic oxide (as I first thought). More likely it is cement, which was delivered in barrels before the double paper bags of more recent years.

May 1991

On several occasions since then, I have been underground in the old workings (a potentially very dangerous thing to do), though most openings were blocked off even then. It was a real eye opener to catch a glimpse of the conditions in which the old time miners worked and to see the mineral veins in their natural condition in places in the rock walls.

As you will soon discover when you start reading about the Ottery, there were two main stages in the history of the mine. The tin stage began during the mining boom at Vegetable Creek (now called Emmaville) which commenced in 1872. Prospectors scoured the district, one of whom (Alexander Ottery) discovered the outcrop of the cassiterite-bearing veins sometime between 1875 and 1881. The mine was opened up in 1882 and the Glen Smelting Works was established to extract metallic tin. The site of the smelters is at the junction of the Emmaville-Deepwater and Torrington roads (Tent Hill).

From The Mineral Industry of NSW (EF Pittman 1901)

Eventually mining tin became unprofitable and the site passed into the hands of the firm William Cooper and Nephews (Australia), who then mined the arsenopyrite ore bodies to produce arsenic oxide which was widely used in the manufacture of sheep dip (1920’s on). This is the time when the surviving condensation chambers and chimney were constructed. There has been a lot of investigation of the site in more recent times and on several occasions when passing by on the way to Torrington I’ve observed drilling in progress on the hill. No doubt the price of tin is the key to any future mining there.

From The Tin-Mining Industry in NSW (JE Carne1911)

You could never call the geology of a site like this “simple”, but basically there are at least 5 quartz veins associated with fissures in a body of granite which intrudes claystone and tuff. This granite is probably related to the Mole granite to the north around Torrington. Arsenopyrite (FeAsS) and cassiterite (SnO₂) were the main ore minerals extracted, but pyrrhotite (Fes) and pyrite (FeS₂) are also present. As is common with such ore bodies, many other minerals have been identified in the ore, but are unlikely to be found as hand specimens.

To gain a better understanding of this place, and to see how it fitted in to the wider mining field, there are many good references you can download. Here are just a few.

A compendium of documents assembled by the Geological Survey of NSW may be found in DIGS (reference number R00045777). Doing a search in DIGS using the location “Tent Hill” and keyword “Ottery” will turn up much more. Of particular interest in the compendium is a document written by Harry Julius, whose father was the mine manager in the arsenic mining days.

The Minerama book title Cassiterite (1984) may be downloaded from here (doesn't work). See the part dealing with Emmaville in particular.

The Tin-Mining Industry in NSW 1911 by JE Carne (DIGS reference R00050677) was written near the end of the tin mining stage and has a good section on the Ottery Mine.