CBJ: Madison's unakite one of a kind rock - The Daily Progress: News

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CBJ: Madison's unakite one of a kind rock

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Posted: Monday, November 3, 2008 4:31 pm | Updated: 5:11 pm, Thu Jan 24, 2013.

SYRIA - Jimmy Graves crosses a concrete bridge over the Rose River and vanishes into a patch of fall-tinged shrubs.

He appears again minutes later, a stone in each hand.

The area has been pretty well picked over by rock hounds seeking chunks of Madison County’s geologic pride, the dense granite called unakite.

But Graves can still spot some occasionally, and this fall day yields a few fist-size chunks and a cobble the size of a toy football.

Rinsed of caked mud and dried algae, the stones show their colors: green and pink, with silvery gray flecks.

Unakite - named after the Unaka range on the Tennessee-North Carolina line where it was first identified - is a visual treat. Its color combination makes it irresistible to collectors who carve and polish it into beads, paperweights and bookends.

Hunting for it along the Rose River is a popular pastime of the tourists who visit Jimmy Graves’ family business, Graves Mountain Lodge, for a meal or a weekend.

On a sunny fall afternoon, it’s easy to get caught up in the search without stopping to think about the origins of these pretty stones.

But the geologically curious might delve deeper - about 10 miles deep, according to College of William & Mary geology professor Christopher “Chuck” Bailey.

That’s where the unakite story began 300 million to 400 million years ago, in a pressurized layer of hot rock deep in the Earth’s crust.

As plates squeezed up to form the Appalachian Mountains, Bailey says, hot chemical-laden water percolated through a hard layer of feldspar buried under miles of younger rock.

The watery brew was about 550 to 750 degrees Fahrenheit - not hot enough to melt the rock, but hot enough to alter it.

Iron and calcium changed some of the feldspar into a different rock altogether, the green stone epidote. Potassium turned adjacent patches of feldspar pink. And grayish quartz filled in the gaps.

Over the next several hundred million years, the rock on the surface eroded and moved east toward the Atlantic Ocean, helping form what’s now Virginia’s Coastal Plain. As layers above it disappeared, the deep rocks that included patches of unakite became cooler and shallower.

At last they were left uncovered, and they jut throughout the Blue Ridge Mountains today.

Unakite can be found in spots all along the eastern Blue Ridge, Bailey says.

He estimates that unakite makes up 1 percent to 5 percent of the granitic rock in Madison County. The biggest pieces Bailey has seen are 2 feet or 3 feet in diameter; most are much smaller.

But the county is mentioned in early geology journals, and the area captured rock hunters’ imagination.

In the 1950s, Jimmy Graves says, unscrupulous rock hunters persuaded private land owners to let them hunt for souvenir samples. Before anyone knew it they’d carried away truckloads of the stone, which they shipped to Japan for a then-considerable 50 cents a pound.

There’s still unakite to be found in Madison.

Much of it is a protected natural resource as part of the Shenandoah National Park, and it’s off-limits even to casual collectors.

But rock hunters still find it along stream beds, especially after storms. In 1995 and again in ’96, heavy rain washed a slurry of mud and rock down the mountains.

When the weather cleared, the rinsed-off pink-and-green stone could be found all along the Rose River, Graves said.

Local artisans have made some of the polished stones into necklaces and earrings that are sold in Madison County craft fairs.

Most people who hunt for raw unakite or buy polished pieces just appreciate its smooth feel and colors without worrying too much about how the rock got that way, Graves says.

“It’s just the way Mother Nature made it.”

- Associated Press

© 2014 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

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