Pyrrhotite and Crumbling Foundations

Within the state of Massachusetts, the natural mineral pyrrhotite and its potential to cause concrete structures to fail have become an increasing concern for homeowners. It is not known for certain how many homes are affected by pyrrhotite-contaminated concrete foundations, but a 2019 report estimated that roughly 2,000 homes in western and central parts of the state may be affected [6]. Given the problems' extensive effects and financial burden on homeowners, the Massachusetts Geological Survey has made it a priority to combat this issue.

 

What is the Massachusetts Geological Survey Doing? 

MGS has worked closely with the Massachusetts Department of Transportation (MassDOT) to write regulations that will dramatically reduce the likelihood of corrosive sulfide minerals like pyrrhotite making their way into concrete mixes used for structures like bridges and home foundations. The State Geologist is responsible for reviewing Geologic Site Reports for all gravel quarries in the state that receive licensure from MassDOT.

 

How Pyrrhotite Affects Homes

When exposed to moisture and oxygen, pyrrhotite oxidizes and undergoes a series of chemical reactions, forming iron oxide minerals, sulfate minerals, and sulfuric acid as by-products. This process weakens concrete, causing cracks to form. If this occurs to a concrete structure like a home foundation or bridge abutment, the structure must be replaced.

What is Pyrrhotite?
Pyrrhotite is a naturally occurring iron sulfide (FeS) mineral that can be found in igneous and metamorphic rocks. The mineral can be identified by its metallic bronze luster and its similar appearance to pyrite (fool's gold), another iron sulfide mineral [2].

The Science Behind Crumbling Foundations
When pyrrhotite is present in concrete, the sulfuric acid produced from its oxidation can trigger what is known as an internal sulfate attack,  reacting with various components of the concrete. Specifically, the acid reacts with the portlandite in the concrete to form expansive secondary minerals such as gypsum, ettringite, and thaumasite. Importantly, these minerals occupy more volume than the original compounds, resulting in the exertion of internal pressure on the concrete structure, leading to bulging, cracking, and eventual structural failure of the concrete [3]. 

Costly and Complex Repairs
Due to its destructive impact on concrete structures, if found in a home’s foundation, pyrrhotite can result in widespread structural deterioration of the concrete, leading to significant damage to the home’s foundation. If a home's foundation has been impacted by pyrrhotite or has tested positive for the mineral,  the only safe and effective way to prevent further damage is to lift the house and completely replace the concrete foundation. However, this process can be costly, ranging from $100,000 to $250,000 [4]. Greater concern arises given most insurance companies will not pay for damages attributed to pyrrhotite as they occur over a long period of time, rather than from a sudden, devastating event [5].

This is an image of crumbling concrete from pyrrhotite
In this July 1, 2019, photo, contractor Don Childree holds a piece of concrete containing pyrrhotite that he pulled from the crumbling foundation of a home in Vernon, Conn. (Ted Shaffrey/AP)

 

Where is Pyrrhotite Located?

The geologic map below shows the occurrence of sulfide-bearing rocks within Massachusetts, which could include the mineral pyrrhotite. However, the exact occurrence and distribution of pyrrhotite within these rock units and the state is still uncertain.

Map of Sulfide-bearing rocks within the state of Massachusetts
Areas shaded in red indicate the presence of sulfide-bearing rock formations within Massachusetts. Map dataset by the U.S. Geological Survey [6].

 

Where are Homes in Massachusetts Affected?

In 2019, the Massachusetts Legislature's Special Commission to Study the Financial and Economic Impacts of Crumbling Concrete Foundations due to the Presence of Pyrrhotite published a report identifying areas that were most at risk for pyrrhotite contamination. During the late 1980s to 2015, some homes built during this timeframe may have used concrete containing aggregate sourced from quarries that were later found to contain pyrrhotite [7]. 

Below are Massachusetts cities and towns that are most likely affected based on proximity to the plant that distributed the pyrrhotite-contaminated concrete.

Most at Risk (towns within a 20-mile radius of the concrete plant):
Wales, Holland, Southbridge, Sturbridge, Brimfield, Palmer, Monson, Hampden, Wilbraham, Springfield, Longmeadow, East Longmeadow, as well as parts of Dudley, Charlton, Brookfield, Warren, Ludlow, Ware, Belchertown, and Agawam [7].

Moderate Risk (towns within a 30-mile radius of the concrete plant):
Southwick, Westfield, West Springfield, Holyoke, South Hadley, Granby, New Braintree, North Brookfield, Spencer, Leicester, Webster, Oxford, and Hardwick [7].

Map of homes that are most likely affected based on distance to mine
Map showing the areas potentially affected by concrete containing pyrrhotite based on proximity to the supplier. The area shaded in red is the towns that are most at risk (20 miles from the plant) of concrete containing pyrrhotite, the area shaded in orange is towns with a moderate risk (30 miles from the plant), and the yellow shaded area is towns that are at less of a risk (40 miles from the plant) [7].

 

Additional Resources

Articles:
Signs of Pyrrhotite in Foundations: What Massachusetts and Connecticut Homeowners Need to Know

Pyrrhotite and Crumbling Foundations

Understanding Pyrrhotite Foundation Problems in Massachusetts Real Estate: What Every Home Buyer and Seller Needs to Know

Massachusetts estimates $350M needed to fix 2,000 homes with crumbling foundations

Fool’s Foundation: The Little-Known Crisis That’s Costing Homeowners Thousands—and Why Massachusetts Is Finally Paying Attention

Calls for lawmaker help as more Massachusetts homeowners face crumbling foundations

Pyrrhotite Testing:
Laboratories Capable of Conducting Pyrrhotite Testing and Examination
 

 

References

[1] J. Kinney , “$350m needed to fix 2,000 homes with crumbling foundations,” masslive, https://www.masslive.com/news/2020/01/massachusetts-estimates-350m-needed-to-fix-2000-homes-with-crumbling-foundations.html (accessed Nov. 4, 2025). 

[2] “Pyrrhotite: Mineral Information, data and localities.,” mindat.org, https://www.mindat.org/min-3328.html (accessed Nov. 4, 2025). 

[3] J. Duchesne, A. Rodrigues, and B. Fournier, “Concrete damage due to oxidation of sulfide-bearing aggregate: a review of recent advances and limitations,” RILEM Technical Letters , https://letters.rilem.net/index.php/rilem/article/view/138/141 (accessed Nov. 4, 2025). 

[4] “Connecticut’s Crumbling Concrete ,” FEMA, https://www.fema.gov/case-study/connecticuts-crumbling-concrete (accessed Nov. 4, 2025). 

[5] “Does homeowners insurance cover Pyrrhotite-related damage?,” MKC ASSOCIATES HOME INSPECTION, https://www.mkchomeinspection.com/faqs/does-homeowners-insurance-cover-pyrrhotite-related-damage?utm_source=chatgpt.com (accessed Nov. 4, 2025). 

[6] Mauk, J.L., and Horton, J.D., 2020, Data to accompany U.S. Geological Survey Fact Sheet 2020-3017: Pyrrhotite distribution in the conterminous United States: U.S. Geological Survey data release, https://doi.org/10.5066/P9QSWBU6 (accessed Nov. 4, 2025).

[7] Special Commission to Study the Financial and Economic Impacts of Crumbling Concrete Foundations due to the Presence of Pyrrhotite, Crumbling Foundation Final Report, https://www.longmeadowma.gov/DocumentCenter/View/4345/Crumbling-Foundation-Final-Report-December-31-2019 (accessed Nov. 4, 2025).