Main source of helium is :

The main source of helium is natural gas deposits in the Earth's crust. Helium is typically found in small quantities as a trace component in natural gas reservoirs. When natural gas is extracted from these reservoirs, helium is often co-produced as a byproduct.

Helium is relatively rare on Earth, and its production is limited to a few regions with significant helium-rich natural gas deposits. The United States, particularly the state of Texas, has historically been a major producer of helium. Other countries like Qatar and Algeria also have significant helium reserves.

It's worth noting that helium is a non-renewable resource, and there have been concerns about its long-term availability and conservation due to its critical importance in various scientific, industrial, and medical applications. Efforts are being made to recover and conserve helium during natural gas extraction to ensure a stable supply for the future.