Searles' late husband purchased the New Hampshire property in 1960 for US$20,000 ($28,371), hoping to continue the mica mining operation. But after the federal government stopped subsidising the industry, leaving domestic mines unable to compete with the overseas market, the couple decided to open the property to the public.
Since then, a steady stream of school groups and tourists from around the world have paid admission to poke around and collect as many rocks as they can carry.
While adults often saw "just plain old rocks", the children were quite knowledgeable, Searles said.
"They were well taught in school and they have a great curiosity, naturally, and this is a wonderful spot for them," she said. "I used to get a big kick out of the kids because they were so enthusiastic."
The mine was discovered in 1803 by Sam Ruggles, who reportedly kept it secret for years and used to transport the mica, a layered mineral, in the middle of the night to Portsmouth.
From there, the transparent sheets were shipped to England, where they were turned into windows for ships, woodstoves and whale-oil lamps. By the early 1930s, an estimated US$12 million worth of mica had been removed.
Since then, the mica has been used for electrical insulation, roof shingles and cosmetics, and in later years, in scouring powder.
As a tourist attraction, the mine attracts thousands of visitors from May to October. Douglas Martin, of Keller Williams Realty, said several potential buyers have expressed interest.
"People are interested in buying something so they can make a living, maybe work six months of the year and go to Florida," he said.
Fellow listing agent Beth Decato Beaulieu has also heard from another mine owner, as well as some who want to keep the tourist attraction but expand in new directions, perhaps adding a campground.
"There's even been some discussion of a mountaintop restaurant and making it a full-day attraction that might bring Grafton to another level," she said. "I just hope that someone who purchases it knows the value it has had for all the generations that have gone through there."
The mine is not open this northern spring and summer, except for June 18, when it will host a free open house for the public.
"It's just time for me to stop working," said Searles, who has run the attraction with her daughter and other family members. "I hope someone enjoys minerals and will enjoy the mine as much as I did."
Moshe Miller visited the mine with his parents as a child and has returned several times with his wife and children. The minerals they've collected over the years are prominently displayed in their New York home, he said.
"We have a special collection from each of our visits, marked by year," he said. "It's a lot of weight to take back from New Hampshire to New York - it makes the car heavier - but we bring it back to remind us of our trip."
Miller said he hopes the new owners retain the tourist attraction.
"The idea that we wouldn't be able to go there again is devastating," he said. "We love the place."
- AAP
