25 Investigates: A little-known mineral found in concrete is causing MA home foundations to fail

David Seaver first learned of cracks in his basement about a decade ago.

“I put a French drain in my basement about 10 years ago and the guys that did it said ‘your foundation’s got a lot of cracks in it,’” the retired mailman from Munson told 25 Investigates. “Then more and more cracking started.”

So when he recently learned that concrete contaminated with pyrrhotite had been found in his town and others nearby, he took immediate action and had his foundation tested. The surest way to confirm the presence of pyrrhotite in concrete is to remove a chunk of a home’s foundation and have it sent to a lab.

“If it is the problem, it’s only gonna get worse. It’s gonna crack more and then the house is gonna eventually collapse,” Seaver said. “I planned my retirement for my retirement. I didn’t plan on, you know, spending two-or-$300,000 on a foundation for my house.”

Pyrrhotite is a mineral that ended up in certain batches of concrete poured into foundations of homes. It is considered a geohazard in concrete because over time – typically 15 to 20 years - it begins to expand and break apart. So far, it has been detected in nearly 2,000 homes in central Massachusetts towns along the Connecticut border, as far east as Holden and Grafton.

A 25 Investigates crew was present when Seaver’s foundation was tested in mid-October.

“This type of cracking here with the horizontal and vertical would definitely raise a red flag,” said Tim Heim, president of the Connecticut Coalition Against Crumbling Basements, referring to the cracks on the basement walls of the Seaver home.


Heim took us through the initial process, which includes drilling into the foundation.

“We’re going to go in seven inches deep; it’s three-inch in diameter,” he showed our crew.

After about a half-hour later, Heim pulled out a cylindrical concrete sample from Seaver’s foundation. The hole was then filled and patched.

“You know, this is personal for me,” Heim said. “This is the beginning stages for Massachusetts. I’m looking and this is bringing flashbacks to me when I first began.”

Heim started doing this work to pay to fix his own pyrrhotite-contaminated foundation. His home, located right across the border in Willington, Conn., is among the nearly 35,000 homes impacted by pyrrhotite in the Nutmeg State.

The only confirmed source of the faulty concrete is an old quarry in Willington, Conn. A now-defunct concrete company mined it between 1983 and 2015. The quarry sits on a massive vein of pyrrhotite that runs up the northeast into Canada.

“It’s unclear as to how many [Massachusetts] homes might be affected beyond the homes that got the material from Willington,” said Jonathan Gourley, a geologist and professor of environmental science at Trinity College in Hartford. “Material was clearly brought over the border into southern Massachusetts.”

In 2018, Prof. Gourley and his colleagues started a pyrrhotite testing program to help homeowners in Connecticut. It has since become a valuable resource for this issue, testing core samples from homes in Connecticut, Massachusetts, Canada and beyond.

A 25 Investigates crew watched as Prof. Gourley processed the core sample taken from David Seaver’s home in his lab in Hartford.

“Unfortunately, the Seavers do have pyrrhotite in their foundation,” Prof. Gourley told investigative reporter Ted Daniel. “Many of the southern Massachusetts borders towns are showing more and more signs of deterioration to the pyrrhotite.”

Gourley added that it’s possible concrete quarries in Massachusetts may have also spread pyrrhotite. If so, he fears the crumbling crisis may have only just begun in the commonwealth.

25 Investigates checked in with Dave Seaver following the troubling results. While disappointed, he’s hopeful.

“This is like a big mess. I’m not mad. This is gonna take a while, so I’m just being patient,” he said, adding that the cost of fixing his foundation could be double what he paid for his home.

For resources or more information about pyrrhotite in concrete foundations, contact the Massachusetts Residents Against Crumbling Foundations via their website or on Facebook.