SANFORD — Thick bands of bluestone run under hillsides west of the Catskills — sturdy, pretty stones suitable for high-end walkways, fireplaces, and patios.

Bluestone sells well, but it can be hard work getting it out. On a recent day, Mitchell Bush’s mining crew sledgehammered big slabs and hand-loaded them on to pallets in an open pit under the midday sun. Mr. Bush has worked more than a 100 mines in his career, but he never knows how deep a deposit extends into a hillside. He never knows when he’ll hit the mother lode.

“I’m hoping this will be a fairly large vein here,” Mr. Bush said, standing by an exposed ledge of bluestone. “Even with 40 years experience, I’m conservative in my estimates.”

Despite the uncertainty, dozens of miners like Mr. Bush have recently been scraping away at the these rural hills around Binghamton. Amid higher demand and streamlined regulations, state figures show a modest bluestone boom over the past decade in New York.

Bluestone is a $100 million a year industry statewide. Almost all of it taken in New York comes from mines across from the northeast corner of Pennsylvania. The area is speckled with overgrown cavities in the sides of hills, signs of old open-air mines dating as far back as the 19th century.

Despite the name, bluestone can be dusty gray or greenish or ruddy. Across the state line it’s called Pennsylvania Bluestone, but it’s the same stuff: sandstone laid down more than 360 million years ago. Buried layers of bluestone can be taller than a full-grown man, but horizontal fractures running through the rocks make it possible to break off thinner slabs that work well for backyard patios, walkways, and fences. Some people use it for kitchen countertops. Bluestone prices vary, but it can offer a natural, middle-range product between concrete and higher-end granite.

“The demand is there,” a representative of Sammarco Stone & Supply in Westchester County, Bud Passino, said. “We’re moving trailerloads per day.”

Mr. Passino said bluestone demand has increased “tremendously” over the past decade — a time when many Americans upgraded their homes. A big question is whether demand will drop off this summer with the weak economy. Mr. Passino said it’s too early in the season to tell, though Mr. Bush said there are signs that demand is leveling off.

Mr. Bush comes from a line of miners dating back to a German ancestor who noticed the rich geology of upstate New York while serving as a mercenary soldier for the British during Revolutionary War. When Mr. Bush started his own career in 1969 with his pickup and hand tools, the job wasn’t all that much different from the grunt work performed by his immigrant ancestor. While miners today use forklifts and diamond-tipped saws, Mr. Bush’s four-person crew still does a lot of lifting.

“It works muscles you didn’t know you had,” Marilyn Kerwin said on a break from loading. Small and strong with short-cropped hair, Ms. Kerwin boasts of being the only female bluestone miner around, as far as she knows.

Ms. Bush’s Simply Stone LLC operation is typical in the sense that he dispatches small crews to isolated pits which can be as small as an acre or two. This has made it hard, historically, for the state Department of Environmental Conservation to regulate bluestone mines. They often work under the radar.

“Basically, they wanted to be left alone and go up in the hills and scrape out a living,” director of the agency’s mineral resources division, Brad Field, said.

Mr. Field said that when Pennsylvania began tightening up its bluestone oversight in 1996, some miners there migrated over the state line to New York. That’s when New York regulators noticed instances of environmental damage.

Mr. Field said that many of the violations involved “overburden,” the layer of dirt and rock that is cleared off before the bluestone beneath can be mined. Miners are supposed to put unused earth back in the cavity when they’re done. Some rogue operators were dumping it over the sides of hills.

Even after decades of mining, Mr. Bush believes there are tons of bluestone to be found in the hills. Though after a two-century-plus run, there won’t be a Mr. Bush removing it that much longer. At 56, Mr. Bush is closer to the end of his career than the beginning, and his two daughters are not interested in mining.

“Unfortunately, it’s going to end,” Mr. Bush said. “I’m heartsick about it.”