Uranium deposits are classified by the cost of extraction, which determines their economic viability. The internationally recognised classification system uses the following categories:
| Category | Cost of Extraction (USD/kgU) | Description |
|---|---|---|
| Reasonably Assured Resources (RAR) | < $130 | Known deposits with well-established geology; highest confidence |
| Inferred Resources | < $130 | Deposits inferred from geological evidence but not yet fully delineated |
| Prognosticated Resources | Variable | Expected to exist based on geological knowledge of known deposit types |
| Speculative Resources | Variable | Thought to exist based on indirect geological evidence |
The total identified resources (RAR + Inferred) recoverable at costs below $130/kgU are estimated at approximately 6.1 million tonnes of uranium — sufficient for over 100 years of supply at current consumption rates. However, exploration spending is cyclical and closely tracks the uranium spot price: when prices are high, exploration expenditure increases and new deposits are discovered; when prices fall, exploration contracts sharply.
Uranium exploration uses a combination of geological mapping, airborne radiometric surveys (detecting gamma radiation from uranium daughter products), geochemical sampling (soil and water analysis), and exploratory drilling. The discovery of a new deposit typically requires 5—10 years of exploration and assessment before mining can begin.