Report on a Trip to the Avoca District, Tasmania
Locality Bulletin No. 1
Introduction
Fickle thing, the weather. And cars.
On the Thursday morning, two days prior to the planned weekend trip to the Avoca district in
northeastern Tasmania, I was driving through six inches of snow on my way to work. And this was at a
much lower altitude than the Aberfoyle Mine. Didn’t bode well. But, in traditional Tasmanian Spring
weather ways, the temperature rose to around the 19oC mark for the weekend, and there was no sign of
snow at all on the Sunday up on the Ben Lomond plateau.
As for cars, I didn’t realise that I was driving a car with a blown head gasket on the Thursday, found out
Friday, and had to borrow my daughter’s car for the weekend (thanks Laura). Needless to say, this was
the prompt to get rid of the Subaru Outback (having suffered two clutch replacements, two blown head
gaskets, two windscreens, and other painful repairs, in only five years) and get myself a new car. Now the
proud owner of a Nissan X-Trail.
The Avoca District is in the Fingal Valley in northeastern Tasmania, about 2.5 hours drive north from
Hobart. The Fingal Valley is best known (geologically speaking) for it’s coal, with some mines still
producing. These mines have also provided some mineral specimens with calcite and stilbite from the
Stanhope, heulandite, stilbite, calcite and pyrite from Merrywood. Other mineral occurrences in the
region included gold at Mangana (the first payable gold in Tasmania), tin and wolfram at a number of
mines in the area, and a barium-bearing bright red heulandite-Ca in carbonaceous Triassic mudstone from
a diamond drill hole near Fingal.
There was a large turnout for this trip, one of the largest that I can remember, with around thirteen
vehicles. We decided to go to Royal George first, in case there were access problems due to snow up in
the higher districts, and left Avoca in convoy.
Royal George Mine (573500E, 5368300N)
The lodes of this mine were discovered in the 1880s but it wasn’t until 1911 that any serious work was
undertaken. The period through to 1929 produced around 900 tons of concentrated tin ore. I cannot find
any later reports so I do not know how much longer the mine was operated.
The main rock type in the area is a coarse-grained granite stock,
with dykes of graphic granite, pegmatites, greisen and porphyry
rock. All of the dyke rocks are traversed by veins of quartz from
a few millimetres to around three metres across. The
mineralisation occurs in these veins.
Access to the mine workings is via a track, too rough for my
daughter’s car (she would have killed me!) but easy enough for
4WD or vehicles with enough clearance. The workings
themselves consist mainly of an open cut about 280 metres long,
25 metres across, but tapering to 3 metres wide at the ends, and
up to 13 metres deep. There is an adit (which is home to an owl,
nice “surprise” for a couple of collectors!), a shaft and a drive
about 25 metres below the open cut, a number of trenches, and
dumps.
Andrew Tuma in the open cut
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© Steve Sorrell, 2002
5/03/2004
Report on a Trip to the Avoca District, Tasmania
Locality Bulletin No. 1
Further down the hill, where we had left most of the cars, were some remains of the mine plant and
machinery, mainly concrete foundations and rusting iron. The equipment used, which was considered
obsolete even at the time, consisted of two Cornish-type boilers providing power to two horizontal highpressure engines, a steam engine that drove the milling and concentrating plants, a second that provided
power to the crusher, the winch at the pit head, and a pump at the river. The milling plant consisted of 30
stampers in three batteries of 10 heads each. This plant crushed up to 700 tons per six-day working week.
The best find of the day was of a ball of schorl which contained a small cavity with bright green
torbernite crystals found by Mike Luttrell. Although small, it was very aesthetic (I say was, unfortunately
the specimen had an accident and is no more). There was plenty of torbernite in this veins, but in most
cases, there was not enough room for good crystal growth. Some cassiterite was found, including a
specimen from down at the plant workings. Interesting doubly-terminated quartz crystals, with no prism
faces at all, simply bipyramidal crystals, slightly corroded, were found by Peter Harris. Schorl balls were
extracted from a seam of soft crumbly material. These often contain cavities, although usually without
torbernite, but with small green tourmaline crystals. Chalcanthite was found on the dumps by Ralph
Bottrill and Andrew Tuma.
Other minerals recorded from Royal George include: Chalcopyrite, Feldspars, Malachite, Micas, Pyrite,
Topaz
Leona Mine (563950E, 5378500N)
The second stop for the day was at the Leona Mine, an old alluvial tin mine where we were told amethyst
could be found. The Leona leases had been worked out prior to 1923 when the nearby New Henbury
Mine was being established. The New Henbury Alluvial Mining Company took over the water rights of
the Leona Tin Mining Company.
The ore deposits are in alluvial ground on the valley floor in depths of 5 to 13 metres, and contain a little
gold as well as tin. Access to the via a good track, and open forest. The collecting area is in the old
workings along a creek. The level of the creek is probably a few metres lower that before any mining took
place.
As well as amethyst, the area has been well-known to lapidary people for the jasper that can be found
here. Geologically, the area is intriguing. There has been a lot of silica moving around, with overgrowths
of drusy quartz on quartz crystals, and much of the Permian mudstone has been cooked up and silicified.
There were many examples found of fossils (particularly bryozoans, but also some brachiopods) being
found in jasper. The other specimens of particular interest included smoky quartz crystals that had formed
inside brachiopod voids, one with fibrous tufts of an unidentified green mineral, similar occurrences of
colourless quartz, some amethystine specimens, bright reddish carnelian, and a few specimens of
crystalline schorl and muscovite.
Of course, with Andrew around, the rest of us didn’t have to worry about the local wildlife (ie: Tiger
Snakes), because they have such an affinity with him.....
Schorl, Royal George
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Torbernite, Royal George
Unidentified mineral, Leona
© Steve Sorrell, 2002
Andrew’s friend...
5/03/2004
Report on a Trip to the Avoca District, Tasmania
Locality Bulletin No. 1
Day 2...Sunday
Day two saw a few new faces, and some from day one, still a good turnout. We opted to start at the
dumps at Rossarden, and then to move on to Storeys Creek after lunch.
Aberfoyle Mine, Rossarden (562500E, 5388000N)
The Aberfoyle Mine workings are just outside the township of Rossarden, to the north.
Outcropping quartz containing cassiterite had been known since 1916, but it wasn’t until 1926 that any
serious mining operation was undertaken. The mine is named after the Aberfoyle Rivulet, and the
company until very recently when taken over by Western Metals Resources, was one of the major mining
companies in Australia, and operators of such mines as the Cleveland Mine at Luina and the Hellyer Mine
near Waratah that recently closed.
The mine is justly famous for its large cassiterite specimens, occurring in fissure veins that have been
worked down to almost 500 metres. Cassiterite, as well as wolframite and sphalerite, often occur on and
in muscovite that forms at the edges of the veins, with white quartz central cores. Sulphides such as
pyrite, chalcopyrite and others, occur in the quartz itself. Where muscovite is absent, the cassiterite
crystals are attached directly to the walls of the veins and separated from the quartz by material derived
from altered topaz. This is why so many large well-formed specimens of cassiterite have been recovered.
A suggested paragenesis is cassiterite and wolframite forming first, followed by muscovite, topaz and
fluorite, then quartz, arsenopyrite and pyrite, with chalcopyrite and sphalerite forming later, then galena,
scheelite, marcasite and iron oxides. The latest stages of mineralisation was the formation of the
carbonate minerals, and this is evident with many of these species forming in cavities in the quartz.
Access to the site is via a track through an area undergoing rehabilitation, to an area on top of the
extensive dump material, some of which is used as road metal.
Minerals found on the day included cassiterite, wolframite, quartz, dolomite, ankerite, fluorite,
chalcopyrite, chalcanthite and other copper sulphates, sphalerite, and an unidentified olive greenish
mineral, possibly fluorapatite(?), although this is usually found as blue hexagonal crystals from here.
Other minerals recorded include: Arsenopyrite, Barite, Beryl, Bismuth, Bournonite, Calcite, Cordierite,
Fluorapatite, Galena, Glauberite, Hematite, Jarosite, Marcasite, Matildite, Molybdenite, Muscovite,
Pyrite, Pyrrhotite, Rhodochrosite, Scheelite, Siderite, Stannite, Tetrahedrite, Topaz, Triplite
Storeys Creek (560800E, 5390300N)
The Storeys Creek Mine has been operating on and
off since the late-1890s. For the first thirty years or
so, it was worked by small parties of miners
without the aid of machinery, and by working rich
veins of ore through trenching and underhand
stoping. The mine was primarily a wolfram and tin
mine, with large veins containing the ore. The
principal minerals were wolframite and cassiterite
and both occurred in coarse crystalline forms. The
distribution of these minerals was fairly uniform,
however, “bonanzas” weighing many hundred
pounds were found in some places. The ore veins
are infillings of fissures in the country rocks, which
consist of quartzite, slate, tuff, and sandstone, and
consist primarily of massive white quartz.
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© Steve Sorrell, 2002
View from Storeys Creek looking up to Ben Lomond
5/03/2004
Report on a Trip to the Avoca District, Tasmania
Locality Bulletin No. 1
Access to the mine site is via a good road, and the
area is operated by the Education Department. A
caretaker lives on site. The dumps are extensive,
with some rehabilitation work having been
undertaken. Minerals found on the dumps included
cassiterite, wolframite (crystals to 8cm or so),
crystalline quartz, including a central section of a
quartz crystal that measured about 4cm across
(would have been a nice complete crystal), and a
number of sulphide minerals.
On the dumps, shaft on right – Storeys Creek
Other minerals recorded include: Carbonate
minerals, Chalcopyrite, Galena, Gypsum, Hematite,
Marcasite, Matildite, Muscovite, Pyrite, Pyrrhotite,
Sphalerite, Stannite
Arsenopyrite, Rossarden
Scheelite, Rossarden
Jarosite, Rossarden
Cassiterite, Rossarden
Footnote
You get strong winds running through the
Fingal Valley at times...
Ouch!!!
Reverse sceptre quartz, Rossarden
References
Blissett, A.H., 1959: The Geology of the Rossarden-Storeys Creek District, Geological Survey Bulletin No. 46, Tasmania
Department of Mines
McIntosh Reid, A. & Henderson, Q.J., 1929: Avoca Mineral District, Geological Survey Bulletin No. 40, Tasmania
Department of Mines
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© Steve Sorrell, 2002
5/03/2004