Step 1: Understand Fluorite Deposits.
Fluorite, also known as calcium fluoride, is a mineral found in many parts of the world. It is commonly used in the production of aluminum and other chemical processes.
Step 2: Identify the Correct Location.
- Dongargaon, located in Maharashtra, is a known fluorite deposit.
- Other locations like Sonapahar, Mangampeta, and Belka Pahar are not specifically known for fluorite deposits.
Thus, the correct answer is Dongargaon, Maharashtra.
Final Answer:
\[
\boxed{\text{Dongargaon, Maharashtra}}
\]