Page 25 - Demo

Slippery rock Gazette
Vermont Verde
Continued from page 3
‘It’s like a Cracker Jack box’
Vermont Verde’s original quarry is so impressively deep that it’s a tourist attraction. The sheer rock walls step down into the Earth with geometric preci- sion. The walls of the quarry are dark green with white veining, and a pool of turquoise water sits at the bottom, 200 feet down.
The picturesque worksite suf- fers from one major problem, though.
“It takes us about an hour to pull one block out of the hole,” says Peter Fabbioli, Tom’s son and business manager of Vermont Verde. Even after all the planning, drilling, and cutting of each block from the deep quarry, it still takes an hour just to lift one block up to ground level. “It’s very time-con- suming,” Peter says. “So, if you can imagine, we have like 50 blocks down there – there’s 50 hours of crane movement.”
As the quarry team extracted rock for road building, they did so strategically, with a new con- cept in mind. “We’re starting a new area where we are going to go down next to the old quarry,” says Peter.
To convert the deep hole quarry into a drive-in quarry, the crew started 1,500 feet away and 34 feet lower than the surface of the existing quarry, and cut in
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Serpentine — often called green marble — is not. It's harder than marble (Mohs 5 hardness), and doesn’t etch from household acids.
a keyway, working their way toward the existing deep hole.
The ramp into the old quarry will run straight through the cen- ter of a second serpentine lens, which they’ve located via drill- ing and core sampling. This will allow the double benefit of providing better access to the old quarry while also access- ing a whole new deposit along the way. “We’re in a good loca- tion to start,” says Peter, adding, “It’s like a Cracker Jack box. You don’t know what you’re going to find.”
What is Serpentine?
Vermont Verde Antique is a serpentine, and it’s not unlike the coveted prize in a Cracker Jack box, because it occurs as isolated deposits within bedrock of schist and phyllite.
Although serpentine is often called green marble, it’s not mar- ble, nor is it particularly similar to marble. Verde Antique is deep green, rippling with white veins. The stone has a Mohs hardness of around 5, and doesn’t etch from household acids. For those seek- ing the look of marble without the upkeep, it’s a sound option.
Vermont Verde has a some- what complex geologic history, but it’s a fun story to tell.
Serpentine is a metamorphic rock that originates very deep inside the Earth, usually in the lower crust or the mantle, which is a thick zone of hot, semi-solidi- fied rock that lies beneath Earth’s solid crust. Verde Antique ser- pentine began its life as basalt, which is the igneous rock that makes up Earth’s ocean basins.
Fans of geology know that rocks don’t always stick around in their original locations. Around 450 million years ago, the east coast of the U.S. went through a geologic train wreck known as the Taconic Orogeny, caused by a volcanic island chain crashing into the east coast of North America. When land masses collide, the ocean floor that once stood between them gets “subducted” or pushed
The old Vermont Verde quarry is picturesque enough to be a tourist attraction, and also has featured in past Natural Stone InstituteVermont quarry tours.
underneath the continents. But it’s not quite as tidy as that. Some oceanic rocks get scraped up and folded into the overlying sedi- ments, then the whole mass gets plastered onto the leading edge of the continent. It sounds messy, but that’s how Vermont was made.
All told, the landscape around Vermont got compressed by 600 miles, squeezing the rock lay- ers into tight folds and trans- forming them into metamorphic rocks. Slivers of ocean crust, long detached from their ocean, got pushed downward and exposed to hot, mineral-rich fluids. The heat and chemical reactions trans- formed the basalt into serpen- tine, in a process helpfully named “serpentinization.”
Fractures in the rock filled in with calcite and magnesite, cre- ating white veining that hints at how the rock was pushed, pulled, and twisted underground.
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