Albite conditions exist at what range of temperatures and pressures?

• A. Only exists low to moderate temperatures and pressures
• B. Exists at high temperatures and pressures
• C. Exists at extremely low temperatures and high pressures
• D. Exists at marine conditions

Answer: (A)

Mineral stability is controlled by temperature and pressure, and albite—a sodium-rich plagioclase feldspar—is stable in crustal rocks under near-surface to shallow-crust conditions. This means low to moderate temperatures and relatively low pressures, typical of what you find in continental crust at shallow depths and during low-grade metamorphism (greenschist facies). Under higher temperatures and pressures, other minerals become stable and albite fades from the dominant phase, so it’s not the prevailing mineral in high-T, high-P environments. Marine conditions aren’t a defining factor for albite’s stability, so they don’t set its range.