Pyrrhotite distribution in the conterminous United States, 2020
March 26, 2020
In parts of Connecticut and Massachusetts, foundations of some homes are cracking and crumbling. Failing foundations can reduce the market value of a home and lifting a house to replace and repour a foundation is an expensive undertaking. In response, some homeowners are defaulting on their mortgages and abandoning their homes. The culprit is pyrrhotite, which occurs in construction aggregate (crushed stone) that was used as a filler in concrete. When pyrrhotite is naturally exposed to water and oxygen, it breaks down to produce sulfuric acid and secondary minerals, including gypsum, which have larger volumes than the pyrrhotite they replace. The expanded volume of the secondary minerals cracks and degrades concrete.
Pyrrhotite occurs in rocks in many areas of the United States. To help assess the national risk of pyrrhotite in aggregate, the fiscal year 2019 appropriations bill for the U.S. Geological Survey’s (USGS) Mineral Resources Program allocated funds to develop a map showing the distribution of pyrrhotite across the United States. The purpose of this fact sheet is to (1) present a nationwide map that shows where pyrrhotite may occur in rocks in the United States, (2) describe and discuss the factors that control the presence and abundance of pyrrhotite in rocks, (3) provide information on geographic information system datasets that deliver more detailed information on these distributions, and (4) describe U.S. and international standards on aggregate that are designed to prevent failing concrete.
While this map and fact sheet provide general information about the possible distribution of pyrrhotite in the United States, they are no substitute for site-specific characterization and quality control programs designed to ensure that aggregate used in concrete is of appropriate quality for its intended purpose.
Citation Information
| Publication Year | 2020 |
|---|---|
| Title | Pyrrhotite distribution in the conterminous United States, 2020 |
| DOI | 10.3133/fs20203017 |
| Authors | Jeffrey L. Mauk, Thomas C. Crafford, John D. Horton, Carma A. San Juan, Gilpin R. Robinson, |
| Publication Type | Report |
| Publication Subtype | USGS Numbered Series |
| Series Title | Fact Sheet |
| Series Number | 2020-3017 |
| Index ID | fs20203017 |
| Record Source | USGS Publications Warehouse |
| USGS Organization | Central Mineral and Environmental Resources Science Center |
Related Content
Data to accompany U.S. Geological Survey Fact Sheet 2020-3017: Pyrrhotite distribution in the conterminous United States
The mineral pyrrhotite, which is an unstable sulfide mineral, was present in crushed stone aggregate used in concrete foundations of homes in Connecticut and Massachusetts, many of those foundations are failing as the mineral weathers. Because of the substantial costs of lifting homes and replacing their foundations, in 2019 the U.S. Congress directed the U.S. Geological Survey?s (USGS) Mineral Re
Jeffrey L Mauk
Research Geologist
Research Geologist
Email
Phone
John D Horton
Physical Scientist
Physical Scientist
Email
Phone
Carma A San Juan
Physical Scientist
Physical Scientist
Email
Phone
Related Content
- Data
Data to accompany U.S. Geological Survey Fact Sheet 2020-3017: Pyrrhotite distribution in the conterminous United States
The mineral pyrrhotite, which is an unstable sulfide mineral, was present in crushed stone aggregate used in concrete foundations of homes in Connecticut and Massachusetts, many of those foundations are failing as the mineral weathers. Because of the substantial costs of lifting homes and replacing their foundations, in 2019 the U.S. Congress directed the U.S. Geological Survey?s (USGS) Mineral Re - Connect
Jeffrey L Mauk
Research GeologistEmailPhoneJohn D Horton
Physical ScientistEmailPhoneCarma A San Juan
Physical ScientistEmailPhone