Boron-11 is more abundant than boron-10 in nature. About 80% of naturally occurring boron is found as boron-11, while boron-10 makes up the remaining 20%.
The reason for this distribution lies in the nucleosynthesis processes that occur in stars and during supernovae. Boron is primarily produced through the cosmic ray spallation of heavier elements, resulting in a natural abundance that favors boron-11, which is more stable than boron-10.
In practical applications, this difference in natural abundance means that boron-11 is often the isotope relied upon for most purposes, including its use in various chemical compounds and materials.