Here's why:

* Geological Formation: Uranium is a naturally occurring radioactive element that forms in specific geological environments. It's often found in igneous rocks, where it's concentrated during the cooling and crystallization process. It's also found in sedimentary rocks formed from eroded igneous rocks, as well as in hydrothermal deposits where hot water solutions carry and deposit uranium.

* Ore Deposits: Uranium deposits are typically found in underground mines. These mines are specifically designed to access and extract uranium ore.

* Exploration and Mining: Mining companies use various geological and geophysical techniques to locate uranium deposits. This includes aerial surveys, ground-based surveys, and drilling.

Note: While uranium is found underground, it's not always readily accessible. The concentration of uranium can vary significantly, and it's often necessary to process the ore to extract the uranium.