The Mintaro slate quarries are located two kilometres west of the town. The mining of slate played a vital part in maintaining the life of Mintaro after the cessation of copper transportation through the town. The quarry has continued to be a major employer of local labor.
Slate was first discovered in the early 1850s on part of Section 178, land which belonged to Peter Brady. The flagstones were outcropping in-the bed of the creek which traverses the section. In 1856 Brady leased the slate bearing area to Thompson Priest, a Mintaro settler who began excavating the No. 1 quarry adjacent to the site of the original discovery. During the 1860s the land changes owners – from Brady to John Smith – but Priest continued to work the quarry. He built a house and office in Mintaro and a small office and foreman’s house at the quarry. Ruins of Priest’s quarry buildings remain on the site, and the house in the town is still in use.
Mintaro slate was exhibited at the London International Exhibition of 1862 and “received the very highest awards, being classed as superior to any slate previously met with, the natural cleavage being equal to planed stone.”
The 1860s and 70s saw Mintaro slate being used extensively in the local area, including Gawler. Wineries in the Barossa Valley and the Clare Valley used Mintaro slate for their fermenting tanks, and the Kapunda Copper Co. used slate tanks for the acid process in refining their ore. Thompson Priest employed 12 men in 1868, and in 1869 the Almanack entries for Mintaro list quarryman as an occupation for several Mintaro residents.
An interesting comparison was made between Willunga and Mintaro slate in the Register, Sept. 30, 1871.
“PAVING SLATES In the pavement in front of the new Post Office there has just been laid down before the principal entrance a fine slab of Mintaro slate measuring 12 x 9 feet. The bulk of the material used is from the Willunga quarries, the produce of which, though not equal to the Mintaro, is considerably less in price, and therefore generally used for the purpose. Mintaro stone has been used for the steps leading to the doorway, and also in other parts ‘of the building”.
Thompson Priest’s method of disposing of his slate at this time was to hold an annual auction on the western boundary of Section 178. The price for the stone was£ 5.0.0 for a cart which could be pulled by one horse, and £10.0.0 if it needed two horses to pull the cart.
The Mintaro cemetery contains a number of slate headstones which are delicately carved and bear Thompson Priest’s trademark.
No. 1 quarry reached a depth of between 80 and 100 feet before the stone became too hard to be marketable. Thompson Priest’s son Edmund had become involved in the business also by this time. The land on which the quarry was located passed into the ownership of Sir Samuel Way in 1879 and was part of his Kadlunga estate.
Some competition arose in 1884 when some local identities including Way’s manager, F.H. Weston, raised a syndicate and leased some land from Way in section 307 immediately north of Priest’s quarry. An attempt was made to establish another slate quarry but this foundered for lack of finance at this stage.
Thompson Priest died in 1888 and the company was taken over by a Melbourne firm but it languished during the depression of the 1890s. The local syndicate tried again in 1893 again with Weston as its chairman. It leased what had been Priest’s area in section 178 and the area in section 307 which it had previously leased, and worked it with the main markets in Melbourne, until the syndicate was reformed in 1911 as the Mintaro Slate and Flagstone Company. The new company bought the land from Sir Samuel Way in 1912, and also purchased the Melbourne agency which had been its distributor for Victoria.
In 1914, when the quarry was visited by the Government Geologist, Mr. L.K. Ward, a third quarry had been opened adjacent to the original No. 1, or Priest’s as it was known. The company employed 25 men at this stage. ·Steam and oil power had replaced hand powered methods for both quarrying and dressing the stone.
The company continued producing quality slate with some fluctuation in market demand during the pre-war period. Post-war the sales slowly increased and in 1958 quarry no. 4 was opened for deeper work.
The company suffered a take-over in 1978 and the quarry itself has since been sold to S.D. Tillett (memorial stone masons) and is continuing to function as Mintaro Slate Quarries.
Mintaro slate has continued to have an extremely high reputation for quality and durability. The uses to which it has been put over time have been varied, ranging from the obvious building and paving applications, billiard tables, wine tanks and troughs, to the less known electrical switchboard uses. Mintaro is a perfect show place for the range of uses to which slate can be put.
The Mintaro quarry is the oldest continuously functioning quarry in South Australia, and in the opinion of Mr. David Young of the Mines and Energy Department, possibly in Australia.[1]