Schist quarry feeds building boom

Cluden Stone Quarry employee Regan Gregg uses the quarry’s new Italian stone-cutting machine....
Cluden Stone Quarry employee Regan Gregg uses the quarry’s new Italian stone-cutting machine. Photos by Mark Price.
The  stone-cutting guillotine shows its tungsten-capped teeth.
The stone-cutting guillotine shows its tungsten-capped teeth.
Grant Middendorf.
Grant Middendorf.

A bit of pressure applied in the right place and slabs of schist at the Cluden Stone Quarry snap apart as cleanly as if they were ice.

It is not surprising, with the quarry's new $100,000 guillotine exerting 120 tonnes of pressure through its 24 tungsten-capped teeth.

Quarry owners Grant and Lucy Middendorf have bought the new Italian-made machine to help them keep pace with Wanaka's building boom.

Mr Middendorf told the Otago Daily Times the new machine was capable of cutting nine tonnes of stone each day, compared with three tonnes by their older machine.

It is also safer to operate.

When the blade drops, the table on which the rock is sitting also drops, revealing another row of teeth directly underneath.

"[The teeth] adjust to the shape of the rock so you are getting consistent pressure over the surface of the rock, which is handy when your rock is curved or sloping.''

It takes three or four months for an operator to become properly skilled and able to pick the grain of the schist reliably.

Mr Middendorf, an explosives expert, and wife Judy, a geologist, bought the quarry two years ago and are producing just over 500 tonnes of cut schist each year.

A big chunk goes to Wanaka but some goes to South Canterbury and elsewhere.

Mr Middendorf gained his quarry manager's certificate in the army and has spent many years drilling and blowing up rock in New Zealand, Australia and the Pacific Islands.

Owning the 69ha quarry property allows Mr and Mrs Middendorf to spend more time working closer to home at Lake Hawea.

The quarry, which has been operating for 23 years, has schist reserves in the Cluden Stream valley measured in the millions of tonnes.

"There's more rock than I can eat in a lifetime,'' Mr Middendorf says.

There are about 10 schist quarries in the region, and generally those nearer the Alpine Fault produce stronger schists.

Stonemasons mostly require schist cut to a width of 150mm for use in house facades, but clients often ask for particular colour variations, ranging from gold to dark grey.

"It is a pretty iconic product around Central Otago.

"For the early miners, that was the only building material they really had ... so it has flowed through to the modern houses.''

Mr Middendorf, who once held the New Zealand distance record for paragliding, jokes that being both a quarry owner and a paraglider made life insurance hard to come by.

However, not only was the safety record of quarrying improving, but a young family meant Mr Middendorf's flying time had also been somewhat reduced.

mark.price@odt.co.nz

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