Quarrying & Mining Magazine
Q&M Quarrying

Hand-made in Wine Country

HUGH DE LACY traces the development of a South Island schist business from the humblest of all quarrying beginnings – breaking rocks by hand.

QM_P18_April_May_2014_1A guillotine developed from an   imported logsplitter was the key piece of equipment that lifted Alexandra Stone’s quarrying business in Central Otago’s Ida Valley out of the crowbar-and-sledgehammer technology on which it was founded. When Bill Grant launched his Otago schist building stone supply business in 1975, his inventory of equipment comprised a crowbar, a sledgehammer, a few wedges and a front-end loader mounted on an old tractor.

It says something for the tractability of the region’s distinctive stone, sought-after nationwide for building and landscaping applications, that Grant was able to make a living out of manual rock-breaking.

A stone-mason by trade, he started his Alexandra Stone business with a partner, but went out on his own after about a year.

Otago schist is a medium grade metamorphic rock that’s a bit like slate, but formed from mudstone and shale by greater seismic temperatures and pressures, resulting in a striated stone with crystallised mica mineral highlights.

The purpose-made bags have handles on them so they can be lifted and loaded by the company’s TCM wheeled front-end loader.
The purpose-made bags have handles on them so they can be lifted and loaded by the company’s TCM wheeled front-end loader.

The larger of these crystals reflect light, giving Otago schist its characteristic lustre and range of colours.

It’s mostly hard   rock, fine to medium-grained and relatively smooth to the touch, and it occurs extensively around the Southern Alps, and particularly in Central Otago.

It has the obliging characteristic of breaking readily at 90-degree angles, which shows its colours and textures off to great effect.

Bill Grant worked his Crawford Hills quarry for 21 years before handing the business over to his son Dave, who has since added the Ida and Poolburn quarries.

The central thrust of that development has been steadily greater mechanisation, something the younger Grant launched into from the moment he took over.

It began with a three-horsepower horizontal logsplitter that his brother Will bought from the giant home improvement chain Home Depot in the United States, and brought home in a container of household goods.

Dave Grant set about converting the logsplitter into a guillotine to replace the sledgehammer and crowbar, and it took him a year or more to get right.

Most of the development work he did himself, or had done by local engineering firms, and in the non-stop process of steady refinement he has ended up today with no fewer   than three guillotines, two stationary and one mobile.

QM_P18_April_May_2014_3With these machines and a staff of five, he’s able to cut the quarried stone into a range of marketable sizes – typically around 180mm thick – for specific applications, from landscaping features to wall-stones, including corners, caps and sills.

The colours range from grey to light and dark brown across the three quarries, with Poolburn supplying a stone coloured lighter than Ida and Alexandra, and the three types able to be mixed by the end-users to produce specific visual effects.

The quarries are generally worked in succession, depending on the colours in demand at the time, beginning with low-powder- factor blasting using Anfo and Powergel.

This usually occurs monthly, producing about 200 tonnes of base product per blast in slabs or plates weighing between 20kg and 100kg, which are shifted to the guillotines by a digger brought in for the purpose.

The guillotines are roller-fed, and it’s this aspect of the operation that Dave Grant is currently focusing his further mechanisation efforts on.

“I still want to get more of a mechanised feed system, but it’s all time and money,” he told Q&M.

QM_P18_April_May_2014_4And   it’s not just labour-saving that’s behind the drive to mechanise: the market that Alexandra Stone services is growing in sophistication, no less than size, and the skill-base of the end-user tradespeople is also changing.

In his   father’s   day the   stone   was commonly   laid by stonemasons, but now it’s more likely to be applied by blocklayers and bricklayers.

“It’s affected us in terms of supply of the product: we’ve had over the years to be more consistent and have a higher-quality output.

“You can’t get away with big boulders and things like that – nowadays it’s all got to be virtually ready to lay,” Grant says.

The tightening of building regulations has also put pressure on the business to focus on quality.

“It’s put more emphasis on us providing a more finished product: where before the skills used to be in the end-user, now there’s more emphasis on us to provide a better product so they don’t have to spend so much time working the stone,” he says.

After being cut to size by the guillotines, the stone is packed, not onto pallets but into bags that are specially made in Thailand, and can hold a tonne of product.

QM_P18_April_May_2014_5Grant got the idea of the bags from using woolpacks, which were about the right size but not strong enough, and they tended to break down after sitting for long periods in the bright Central Otago sunlight.

The purpose-made bags have handles on them so they can be lifted and loaded by the company’s TCM wheeled front-end loader. The product is distributed for Alexandra Stone by trucking companies, with the booming local building markets of Queenstown and Wanaka providing a handy destination.

Demand for the product is also steady in Auckland and other parts of the North Island, while post-earthquake Canterbury is another major market.

Schist has been a signature product of Central Otago since the pioneering and mining days when it was used for everything from housing to fencing, but over the past couple of decades the region has also made a name for itself as the producer of world-class pinot noir wines.

Alexandra Stone is the region’s biggest commercial producer of Otago schist, and lately Dave Grant and wife Suzanne Sinclair have expanded their business interests into the new icon, producing wine from their Shaky Bridge estate near Alexandra.

There wasn’t a pinot noir vine in sight when Bill Grant starting quarrying schist with his crowbar and sledgehammer 30-odd years ago, but then neither were there any rock-cutting guillotines.

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