Gallium is a soft, silvery-white metal identified by the chemical symbol Ga and atomic number 31. Classified as a post-transition metal, it possesses several unusual properties that make it a highly valued element in modern technology. The most notable characteristic of gallium is its remarkably low melting point, which is approximately 29.76 °C (85.57 °F). This temperature is just above standard room temperature, meaning a piece of pure gallium metal will melt readily when held in a person’s hand.
Primary Natural Sources
Gallium is not typically found in concentrated deposits but exists only in trace amounts dispersed throughout the Earth’s crust. It is considered a rare element because it substitutes for other atoms, like aluminum and zinc, in the crystal structure of common ores. Nearly all commercially available gallium is recovered as a byproduct during the refining of other metals.
The primary source is the Bayer process, the industrial method used to refine aluminum from bauxite ore. Gallium is dissolved in the alkaline solution, or “Bayer liquor,” and then chemically separated from this liquid waste stream. A secondary source of recovery is the residue left over from the smelting and processing of zinc ores.
These complex extraction methods underscore why gallium is considered relatively scarce and expensive to source. Less than 10% of the total amount contained in these resources is economically recoverable. The reliance on other metal industries for its supply makes the gallium market highly dependent on global aluminum and zinc production.
Key Commercial Applications
The vast majority of refined gallium is chemically bonded in compounds used by the electronics industry, not as the pure metal. Its most widespread application is in the creation of Gallium Arsenide (GaAs), a compound semiconductor material. GaAs is preferred over traditional silicon in high-speed applications, such as microwave integrated circuits and high-frequency radio components found in satellite communications and cell phones. The material allows electrons to move faster and operate at higher temperatures than silicon, leading to superior performance.
Another compound, Gallium Nitride (GaN), is foundational to optoelectronics. GaN is the primary material used to manufacture blue and white Light-Emitting Diodes (LEDs), enabling energy-efficient lighting and electronic displays. The wide bandgap of GaN allows it to emit light in the blue and ultraviolet spectra, which is also leveraged in violet and blue laser diodes, such as those used in Blu-ray technology.
Gallium compounds also play a role in advanced solar energy capture. Specialty Gallium Arsenide solar cells exhibit high efficiency and resistance to radiation damage, making them the material of choice for spacecraft and satellite power arrays. Gallium is also used as a dopant—a trace impurity that modifies electrical properties—in certain silicon-based solar cells to enhance performance.
Consumer Accessibility
Pure gallium metal is readily accessible and commonly sold online by specialty element retailers and laboratory supply companies. It is often marketed as a novelty item or for educational purposes. The metal is available in small quantities, typically high-purity ingots or spheres, allowing consumers to witness its characteristic melting point firsthand.
While gallium is not considered toxic and is safe to handle, a few precautions are advisable. It can leave a slight stain on skin and surfaces, which washes away with soap and water. It should never be stored in glass containers, as it expands by about 3.1% when it solidifies, causing the glass to crack. Furthermore, gallium is corrosive to aluminum and can compromise the structural integrity of aluminum alloys through liquid metal embrittlement.