Helium (He) is a colorless, odorless, nonflammable gas. Most naturally occurring helium is produced through the radioactive decay of uranium and thorium within Earth's crust, over millions of years. Once it is formed at depth, a carrier gas, such as methane or nitrogen, helps transport helium through subsurface rocks through fractures or faults. The helium then accumulates in porous reservoirs, where it is trapped under impermeable evaporite layers (e.g., salt). Helium often accumulates in the same subsurface reservoir rocks as oil and natural gas; therefore, it is commonly associated with these energy resources.
On Earth, helium is rare. The element’s low atomic mass, with only two protons and two neutrons, means it is light enough to easily migrate through the Earth’s crust into the atmosphere without favorable geologic conditions, as described above. Once it enters the atmosphere, helium's low density allows it to escape and disperse into space. Helium cannot be replenished on human timescales and cannot be manufactured economically.
Simple schematic showing the ideal geological setting for recoverable helium accumulation. Source: geology.com
Helium has unique properties that make it difficult to substitute in many of its uses. It has the lowest boiling point of any element, it is chemically stable, and it remains liquid at extremely low temperatures. Helium is essential for cooling magnets used in MRI machines, particle accelerators, and other advanced scientific or medical equipment. Helium is also used in semiconductor and fiber-optic manufacturing, aerospace and defense applications, welding, leak detection, controlled atmospheres for industrial processes, and lifting gas for balloons and airships.
Easily recoverable helium concentrations are uncommon. Global supplies are limited, and demand remains strong. Helium supply is essential for national security, healthcare, and advanced technology. Therefore, helium is classified by the United States as a critical mineral and a strategic resource: it possesses irreplaceable physical properties, and it is non-renewable and cannot be manufactured. Conservation, recycling, and development of new domestic sources are therefore important components of maintaining long-term helium availability.
Helium in Arizona
Map of northeastern Arizona showing location of major geologic features and fields where there are significant concentrations of helium. (A) Tohache Wash field, (B) Bineh-bi-Keyah field, (C) Pinta Dome field, (D) Navajo Springs field, and (E) St. Johns-Springerville area (including St. Johns dome). Source: https://static.azdeq.gov/ogcc/winter_2003.pdf
In the United States, commercial helium production occurs primarily in gas fields of the western and central states, including Texas, Kansas, Oklahoma, Colorado, Utah, New Mexico, and Arizona. Arizona's extensive evaporite deposits have played a critical role in the accumulation and long-term preservation of helium, and the state hosts some of the highest-grade naturally occurring helium accumulations in the country.
Arizona’s most significant helium resources occur in the northeastern part of the state, particularly within the Holbrook Basin and the Four Corners region, as detailed in a talk delivered by Kurt Constenius and Andrew Payton to the Arizona Geological Society in 2022. For example, at St. Johns Dome (located within the Holbrook Basin), helium is trapped within a four-way structural closure beneath thick evaporite seals, creating one of the world's most significant naturally occurring helium accumulations. Helium concentrations in this area can reach 10% by volume, with an average of 8%; this is much higher than concentrations found in most natural gas fields, which average 0.4%. These enriched concentrations make Arizona’s deposits particularly attractive because helium extraction is generally only economical where concentrations are sufficiently high. Another special quality of helium in this location is that it contains measured quantities of the rare isotope helium-3, which is far more valuable than the much more abundant helium-4 because of its unique applications in quantum computing, cryogenics, neutron detection, and fusion energy research.
Recent exploration and development activity has renewed interest in Arizona's helium potential, especially as global supply challenges have highlighted the importance of reliable domestic sources. Historically, U.S. helium production was dominated by large federal and private helium operations associated with natural gas fields in the central United States. More recently, exploration companies have focused on previously underexplored basins, including areas of northeastern Arizona, using improved geophysical methods, modern drilling technologies, and structural traps to identify commercially viable resources.
The development of helium resources requires careful evaluation of reservoir characteristics, including helium concentration, gas composition, reservoir pressure, porosity, permeability, and the ability to produce gas efficiently. Unlike oil and natural gas, helium is typically recovered as a component of produced gas and requires specialized processing facilities to separate, purify, and store the helium. Due to its association with subsurface gas reservoirs, helium production is regulated through the Arizona Oil and Gas Conservation Commission, even though it is a strategic mineral resource rather than a conventional energy resource.