Outcrops of coal had been noticed in the New Town area in the early 1800s, and it was optimistically hoped that large quantities were available. In 1855, for example, when the Newlands estate was advertised for sale, the description of the estate, (attempting to 'talk up' the value) claimed:
"Coal has been discovered and worked on both sides of this property, there can be little doubt of the fact that the carboniferous formation extends under the whole estate of Newlands a supposition which enhances its value far beyond a mere speculation as landed property only. Upon the known calculation that a square mile of coal three feet in thickness will yield 3,000,000 tons of coal, the probability is, that the surface of Newlands covers a bed of coal equal to 116,000 tons".
In fact, between 1865 and 1890, when the New Town coal fields were most active, only around 50,000 tons of poor quality coal was produced. A limited amount of mining continued sporadically after 1890, but produced only small quantities.
Although most of the mining was in New Town, there were three areas of mining in Mount Stuart. A report for Parliament was prepared in 1884, and the State Library has a copy which includes a map, drawn to a scale of six inches to the mile, showing the locations of shafts and the positions of streets including Augusta Road, Elizabeth Street, the beginning of Elphinstone Road, and Giblin Street (then Scott Street). By careful measurement, and assuming the map was accurately drawn, it is possible to locate the Mount Stuart shafts within 25 metres or so.
There were two shafts in what is now Mortimer Avenue, one at each end of the level part of Mortimer Avenue where there is a dividing strip down the middle of the road. These two shafts are on the plan without any comment - unlike other shafts which are often marked with a name, depth, and whether steam power was provided etc. It is known that there was a mine at, or near, the Lyndhurst property in Elizabeth Street. A senior Mount Stuart resident recalls that an old shaft opened up on the front lawn of Lyndhurst when he was a boy, and had to be backfilled. More recently, building extensions at the back of Lyndhurst uncovered a large cavity which also had to be backfilled. It is possible that the mine entrance was somewhere adjacent to Lyndhurst, and that the two shafts in what is now Mortimer Avenue were for ventilation or to pump water.
Another shaft was located in the level section of Gordon Avenue close to the intersection with Montagu Street. This shaft is marked on the 1884 plan as a "Whim Shaft". A whim was a device commonly used in the last century to provide power for milling or pumping, in which a horse or donkey walks round in circles turning a capstan winch geared to a shaft. (The remains of a whim once used to pump water may be seen at the Woolmers Estate near Longford.) Whether the whim at this shaft was used to pump water or to lift the mine cage up the shaft is not known. This mine was on land owned by Dr Benjafield.
The preliminary exploration work gave rise to optimism: A contemporary newspaper article reported:
"Lately an important discovery, altogether out of the agricultural line, has been made on Dr Benjafield's property. This is the finding of a coal mine. The proximity of the Newton mines led to a ridge of hills in the property referred to being prospected by Messrs Wm Sutcliffe and James Smart. An arrangement was entered into by which the prospectors agreed to pay a royalty on the value of the coals obtained, and operations commenced on the 17th May last. A shaft 6ft. x 6ft. 6in. was sunk, marl being passed through for the first four feet, and after that sandstone to the bottom, which was reached at a depth of 30 feet. Coal was struck on the 30th May, and a drive was put in to a depth of about seven feet towards the south-west. The drive is 2 feet 9 inches at the entrance, and the seam of coal has gradually widened to 3 feet 4 inches, a soft clod of 6 inches in thickness dividing it. The width of the drive is 5 feet, and coal exists on either side, while the roof, being of very hard sandstone, will scarcely require slabbing. Up to the present there has been no trouble with water, the shaft being quite dry with the exception of a slight drift. Hitherto only two men have been working in the mine, and very little expense has been incurred, but as matters progress more capital will certainly be expended, both in labour and machinery. The coal appears to be of excellent quality, as although rather soft, it burns long and brightly. Should coal mining on Dr. Benjafield's farm go ahead, not only will the value of the property in the locality be greatly increased, but the benefit to the community at large will be very considerable, owing to the proximity of the mine to the city ".
Evidently the optimism of the above article was not well founded. The Mines Department Bulletin 64 says: "During the 1880s a small mine was run by Dr Benjafield in the vicinity of Benjafield Terrace. Miners were brought out from Wales to operate the mine, but the venture was not a success.
One of Dr. Benjafield's grand-daughters, born in 1910, recalls that as a girl she remembers the shaft, fenced with a wire fence. Some time after the death of Dr Benjafield in 1917, the orchard property was acquired by Co-Operative Estates Ltd and sub-divided. Presumably the shaft was filled by Co-Operative Estates as part of the sub-division works. The original sub-division plan by W. F. Darling provided a generous open area some 200 feet square in the vicinity of the shaft, at the intersection of Gordon Avenue with Montagu Street.
Another local resident advises that he had always understood that there was also a horizontal adit into the mine from the vicinity of the reserve at the corner of Doyle Avenue and Newlands Avenue.
The third area of mining was adjacent to Augusta Road between the shopping centre and Giblin Street. Here, one of the coal seams outcropped, and the coal was worked by a number of mines in close proximity to each other.
In 1883 a report was prepared by G. Thureau (Inspector of Mines and Geological Surveyor), which described wide variations in the quality of the coal resulting from the penetration of the coal measures by volcanic vents and dykes. Thureau was not impressed with the quality of the coal, and remarks that:
"With an admixture of other fuels they are very useful for the production of quicklime, and for smelting raw iron ores for rough cast iron".
There were said to be six separate seams, with a total thickness of nearly 12 feet. A typical seam was only two feet thick, and the miners worked seams with a minimum height of three feet. The seams ran downhill towards the south west, and there were continual problems with water, which was a major factor leading to the closure of the mines. Without electricity for pumping, ventilation and lighting, mining must have been unpleasant and hazardous. Some shafts were more than 100 feet deep, and probably mining of the seams proceeded uphill, allowing water to flow back to the shaft from where it could be pumped, with a plunger pump in the bottom of the shaft, and an operating rod to the shaft top which could be worked up and down by a horse whim or, in some cases, a steam engine. It was reported that the last two mines to close were each pumping around 18000 gallons a day, and in 1884 a deputation of miners met the Minister for Lands and reported that output must soon cease, owing to water, unless new seams could be found.
The mining operations would have produced a significant volume of waste material, mostly broken rock. This would have been disposed of by the easiest means available, and much was probably dumped in creeks, clay pits and muddy hollows. New Town generally, has probably benefitted from this dumping practice. The reason that the little creek alongside the footpath below the hairdresser's shop at the end of Toorak Avenue has been able to cut a gully two metres deep, is that the creek is running in old fill from Dr Benjafield's mine. Excavation on the site of the new Purity supermarket showed there was a layer of rockfill on top of clay in the area.
There may be disadvantages still evident today. Some subsidence at the ground surface is inevitable above the area where seams were dug out, and it is interesting to note that Thureau stated that mine workings extended up to 200 yards from the shafts. Since mining ended, more than 100 years has elapsed, and it is likely that all ground movements have ended by now. There is still, however, occasional subsidence of old shafts, and even today, one would be well advised not to build where there once was a shaft!