Machele Jones grew up knowing she’d been adopted, and like many adopted children, she longed for years to know more about her origins. She took her first steps toward getting answers three years ago. She’s still reeling from what she found.

First Jones, 45, of New York City, discovered she’d been conceived during a sexual assault. Then she learned she descends from a group of African-born men, women and children who were enslaved at an iron forge in rural Frederick County, Maryland, during the early 1800s.

Both revelations came as a shock, she said, but they’ve placed also her on a pathway toward a form of spiritual liberation — an experience she shares with dozens of “cousins” she’ll meet for the first time this weekend.

Jones is one of about 50 descendants of the 300 or so people who were enslaved at Catoctin Furnace in Thurmont who will gather for a unique “descendants’ reunion” this weekend. Individuals from Maryland, Pennsylvania and other nearby states — and some from as far away as California, the United Kingdom and Australia — will meet at the historic site Saturday for two days of conversation, presentations, meetings and educational hikes.

Jones said she once vowed she’d never visit a place where her ancestors were held in bondage, but she decided to push through the pain.

“I’m nervous, but I’m looking forward to meeting the ‘cousins,’” she said a day before she traveled from New York to Maryland by bus Thursday. “Doing all this has been rocky, but it has turned into a mission for all of us. And I’m looking forward to paying respects to the people in the graves.”

Catoctin Furnace is well known as a landmark of state and national history. Historians have long written about how the first settlers of the Monocacy River Valley, an expanse at the foot of Catoctin Mountain some 70 miles northwest of Baltimore, discovered rich ore deposits in the mid-1700s, sparking a wave of industrialization.

Then four wealthy brothers from Calvert County — James, Baker, Roger and Thomas Johnson — bought land there shortly before the Revolutionary War, and built a blast furnace that could produce large quantities of pig iron. By 1776, it was churning out household items as well as cannon and ammunition to be used in the war, including at the Battle of Yorktown. It remained in use through 1903.

But a crucial part of that history remained untold. It wasn’t until 1979 that archaeologists surveying land, as part of a highway expansion near Thurmont, discovered skeletal remains in the ground. Experts called in from the Smithsonian Institution determined from skull and bone configurations that the deceased were of African descent.

They’d uncovered an African American cemetery on what had been forge property — a surprise to many, given that the area had long been known as overwhelmingly white.

“The history of the enslaved population had been totally forgotten,” said Elizabeth Comer, an archaeologist who serves as president of the Catoctin Furnace Historical Society, which operates out of a cottage on the site.

Comer has spent much of the time since then spearheading research to bring that history to light. She and others combed historic documents that listed enslaved persons (by first name only), cross-referenced whatever information they could gather, and conducted interviews to hear family accounts. And she decided to take advantage of advances in technology, enlisting the help of Smithsonian and Harvard researchers and geneticists from the 23andMe biotechnology company to begin DNA testing of the remains.

Comparing the enslaved persons’ DNA profiles against samples in the 23andMe database, the group identified five genetic families in the cemetery (those found to be most closely related to each other were buried together) and identified nearly 42,000 close and distant relatives who were still alive. 23andMe sent each a notice of the newly discovered connections.

Jones has already given the company a saliva sample for her own family search, and getting pinged about a Maryland connection was a surprise. She reached out to others who shared her DNA traits, established connections, and ended up meeting Comer — but not before waking up screaming one night from a nightmare in which a young girl with a branded face tried vainly to speak to her.

“The more I learned about Catoctin Furnace, the more I believed my ancestors are trying to tell the world their stories,” she said. “This is like a spiritual mission.”

One matter that shocked Jones, who identifies as Black, was learning she is 14% European and that her genetic profile overlaps with that of members of the Johnson family, one of the most powerful slaveholding families in Frederick County. (Thomas, she discovered, had been a member of the First Continental Congress, served as Maryland’s first elected governor, and was a good friend of George Washington.)

“They were making babies” with enslaved women, she said, adding that it’s important, if painful, to preserve enslavers’ full history as well.

Crystal Emory has a similar story. A pale-skinned woman who grew up in the area, she said she always knew the family of her absentee father was African American, and by her 20s she’d heard from her grandparents about her second great-great-grandfather, Robert Patterson, a Free Black man who spent most of his life in the region.

Emory met Comer as the archaeologist collaborated with the Smithsonian to produce a documentary film on the history of the furnace — titled “Forged in Slavery,” it aired on Smithsonian TV and Paramount last year — and the exposure to DNA possibilities supercharged the family research she was already doing.

It turned out that Patterson’s father, also named Robert, had been enslaved at Terra Rubra, the Carroll County plantation on which future national anthem writer Francis Scott Key was born in 1779 — and DNA research has shown, among other things, that Claggett is a cousin to some in the Key family.

More important to Emory, a portrait of Robert Patterson emerged. One of the few Free Blacks who worked at Catoctin Furnace, he was a skilled collier (a worker who made the charcoal that fueled furnaces). He later bought a farm and grew fruit, helped raise at least seven children, and was instrumental in creating a school for African American boys and girls.

The more Emory learned about Patterson, the prouder she became. She even found an old newspaper story in which one of his employers termed him an “abolitionist.” She’s trying to learn more about that.

Emory’s husband happens to be a member of the Claggett family, an influential Maryland clan known for their prominence in the newly formed Episcopal Church, their wealth and their profile as slaveholders.

“He has a rich heritage, but I do, too, in my opinion,” said Emory, 70. “I’m very proud of my heritage regardless of the fact that they were poor people.”

So too is Vicki Winston of Kearneysville, West Virginia. Her mother’s genetic trail, she learned via Comer’s research, leads straight back to a girl who died at about age 4 and whose remains lay in the cemetery — and her own unveiled a connection to a Hanson Summers, a man the historical society’s research had established was an enslaved ironworker who helped create popular stoves and other wares at Catoctin.

She has since visited the furnace site and its museum, where she has “stood where the kitchen and the living room of the slave quarters were,” some of it still standing, and seen some of the pots and skillets men like Summers made.

“I get emotional just talking about it,” said Winston, who plans to visit the cemetery and leave flowers for the deceased little girl this weekend.

Among their activities, descendants will attend a banquet at nearby Claggett Center, a retreat site where they’ll be staying overnight; meet with Angela Crenshaw, the director of Maryland State Parks, to share thoughts about the future of the site; and attend a service in Harriet Chapel, a church that John Brien, a later owner of the forge, built in honor of his wife — and where African Americans and whites are known to have worshipped together in the 1830s.

Comer hopes that members of the public will attend some events and that publicity around the weekend might draw the attention of donors interested in helping the society raise the funds they need to purchase the cemetery, which is now in private hands. (A $50,00 grant from the France-Merrick Foundation has helped.) Should that happen, they’ll donate it to the state “that day,” Comer said.

And for all her trepidation, Jones said she’s very much looking forward to this inaugural reunion.

“This is a story that needs to be told,” she said.