Oamaru Limestone

October 2008
Way back in 1872 Henry Mitchell bought land at Weston, just outside of Oamaru and named the property Parkside after the Parkside Hotel he owned in Caversham. He ran the farm until his death in 1891 falling off his horse at the Weston Railway siding.

Two sons, James and Joseph ran the farm in partnership for a while. Joseph took it on on his own until he died in 1933 from you guessed it..injuries received after falling off his horse .while mustering cattle.

Only son Ivan then took over (the family by this stage isnt too keen on horses.) He bought gear and developed the cropping side of the farm business - although he did hang onto the Border Leicester flock that had been started by his father in 1901.

In 1964 the farm was sold to Ivans two sons Joseph and Derek. Joseph ran the farm in his own right from 1970s. and at the same time developed what has been a lifelong interest in machinery. He bought the first bulk handling combine harvester in the district along with grain drying machinery.

Jo started to do a fair bit of contracting in the area. In 1974 he bought back the lease on the quarry that was on the farm and in 1991 Parkside Quarries Limited bought Taylors Limeworks which was also on the Parkside Farm site.

Oamaru Limestone is known to geologists as Totara or MacDonald limestone. Its about 40 metres thick at the Parkside Quarry and this is typical of deposits in the whole Oamaru district.

Its reckoned that the limestone was formed a mere 35 million years ago while sea covered North Otago. Occasionally shells and other fossils are found in the stone while quarrying. The limestone itself is formed by the shells of marine animals, which built up on the sea floor like a thick blanket. Over millions of years the soft sediment hardened into rock. If it was left a little longer then youd have marble a la Takaka.

Limestone was first quarried in the area in the 1860s. The stone is this area is particularly prized because it is said to be fine-grained, even in texture and free from joints and impurities.

Limestone Blocks have been carved out of the Parkside farm since 1905. The first significant building to use this quarrys limestone was the Oamaru Opera House.

The Parkside Quarry is the last operating quarry in the area and the sole supplier of Limestone building material in NZ. It was previously known as Gays Oamaru Stone Company and latterly Gillies.

Returning the quarry back into family hands was a coup for Jo Mitchell and something hes obviously proud about. He hasnt rested on his laurels however new machinery has seen the quarry output increase significantly.

Customers these days are largely mansion house owners rather than any civic buildings of note. Many of these homes are huge and their owners wish to remain anonymous. The quarry supplies bricks as well as internal and external veneer. They are usually about a month behind on their orders.

The limestone seam is exposed by removing the topsoil and then a digger with a saw attachment cuts through the stone crossways and longways. Then a front end loader comes in and digs the block out. (A bit like putting the knife at the bottom of the fudge tray and lifting it out )

The stones are carted to the mill where they are assessed for quality. Some are rejected because they are too hard or are cracked. The too hard ones can be used for carving. A big 2 ton block is yours for a mere $158 .plus cartage.

The usable blocks are then cut up much like great lumps of wood. Theyre still damp when theyre cut but harden up with exposure to the air. Theyre stacked on pallets and transported out according to job lots.

There are two saws working at the Parkside Quarry theyre tungsten tipped. Its hard work I imagine lifting the blocks on to the saw trolley and bloody dusty.

Their standard end product is a 12 X 4X 6.50 brick. The quarry manager Brett Turnball told me some of the big mansion houses theyre cutting for will take up to 40 pallets of bricks. (At around 1.5 ton per pallet)

The main trick to laying them is making sure where the bed of the stone is. The bed is the horizontal bottom of the stone when it is lifted from the face. If it isnt laid the right way it will crumble.

There is still a bit of splitting and bolstering done with a guillotine. This gives the uneven look that used to be popular but is currently out of fashion.

Jo Mitchell bought the old Taylors Limeworks which was also on Parkside farmland back in 1991. The lime business started when a huge heap of lime dust from the quarry cutting saws was successfully marketed as agricultural lime. (The specs are very good 98.5% pure ). This business has been operating since the 1930s but was slowly developed through the next few decades with the addition of new crushing and drying plants.

Jo has developed the Works adding large bulk storage facilities which mean a truck can roll up and park on the weigh station the driver leap out and load the truck himself with a front end loader and then drive off once the required weight has been achieved.

In the past there was a rail siding that came all the way to the plant but with deregulation of the transport industry thats a thing of the past.

The limeworks has just taken possession of a huge 40 tonne capacity dump truck bought second hand from an Australian mining company which will cart agricultural lime from the quarry to the works. Theyve also bought a screening machine which they hope will help them turn out usable limestone for cattle races.

The farm is roughly 750 acres sheep, beef and cropping. The farm manager is Ivan Mavor.

Bob Wilson is the manager of the quarry and limeworks. Hes a former sportsman playing for cricket for North Otago with the odd game for Otago in the 70's. He runs the accounts and does stuff like work off building plans to help calculate the required amount of stone for a job.

Linda Wilson is Joe Mitchells step daughter-in-law married to Bob. Shes been helping with the marketing of Parkside Quarry for a period ran a garden centre from their property does cut flowers for the market organises the use of their extensive garden as a wedding venue and has been behind a bi-annual limestone symposium.