Rock hounds see the big picture

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Visitor’s this year’s Gemstone Jewellery and Craft Fair will be able to get a closer than ever look at the treasures on display.

The North Otago Rock and Mineral Club, which runs the event, has bought a Microeye microscope that projects the magnified object on a screen.

Club president Karen Aitken said the microscope, made in Mangonui, came with a $5000 price tag, paid for with sponsorship and fundraising.

The fair is the club’s major fundraising event of the year and there will be activities for children – from face painting to geology-themed projects.

There would also be stalls and displays and a few new members often signed up on the day for the Rock and Mineral Club, which had seen a resurgence in interest over the past four years. Ms Aitken said.

“That is how I got started, taking my kids out to field trips.

“I have learnt an awful lot about rocks and minerals since then.”

During the club’s monthly meetings, its members hear from guest speakers, or head out on field trips in the Waitaki district.

Being so close to Dunedin and the University of Otago meant there were plenty of experts to call on, Ms Aitken said.

“We certainly keep an eye on what [the university] is up to.”

The Waitaki Valley and surrounding areas were rich in geological history and diverse to explore, she said.

“We have lots of limestone, gold, the Moeraki Boulders, the Oamaru volcano all within a short distance.”

It was long believed that Cape Wanbrow, south of Oamaru Harbour, was partly built by a monogenetic, or one-off, eruption when that part of the country was still under water, between 30million and 40 million years ago.

But in 2015, an Otago University PhD student released research that found it was not just one blast – or even one volcano – that was responsible for building up the land.

Ben Moorhouse said his findings, published in the Journal of Volcanology and Geothermal Research, revealed the area was constructed by different volcanoes and eruptions, at the same spot but in discrete events that took place millions of years apart.

Waitaki is also famous for a its species of diatoms – a type of single-celled algae with a silica shell.

In some cases, and over millions of years, these shells fossilise, creating a fine powdery substance.

Under a microscope, this powder created beautiful light patterns and it was very popular in Victorian times, Ms Aitken said.

“They didn’t have TV back in those days.”

The Gemstone Jewellery and Craft Fair will be held on Saturday and Sunday at the Scottish Hall. Entry is by gold coin donation.