Resource availability depends on what is known to exist and what can be extracted under current conditions.
The syllabus uses four availability categories. Proven reserves are identified deposits that can be extracted under the current economic and technological conditions. Conditional reserves are identified deposits whose use depends on conditions changing, such as a lower extraction cost, improved technology or a higher selling price.
Hypothetical reserves are undiscovered quantities expected in areas where geological knowledge suggests further deposits, for example extensions within a partly explored mineral-bearing region. Speculative reserves are less certain possibilities in areas where favourable geology suggests a resource but deposits have not been demonstrated.
Keep two questions separate: how certain is the geological evidence, and is extraction feasible? A survey may increase certainty. A price fall may make an identified deposit uneconomic without removing it from the ground. Improved technology can make a conditional deposit usable, but higher costs can reverse that change.
Terminology varies between professional classification systems. USGS classifications call hypothetical and speculative quantities undiscovered resources, rather than proven recoverable reserves. For this syllabus, use the four named categories while keeping their uncertainty clear. Neither a large estimate nor a rising price proves that extraction will be possible, permitted or environmentally acceptable.
Step by step
Check evidence
Is the deposit identified, expected from a known setting, or more speculative?
Check feasibility
Consider technology, price and extraction costs.
Explain a change
State which condition changed and why it moves the deposit between categories.
Worked example: Same deposit, different economics
An invented identified ore body costs $80 per tonne of saleable product to extract. At a price of $60 it is not economic; at $100 it may become economic if the other conditions are satisfied. No new ore was created by the price rise.
Watch out for this
Speculative reserves are guaranteed future supplies.
They are uncertain geological possibilities. Exploration and feasible extraction must come before they can be treated as dependable supply.
Check your understanding
An identified deposit becomes uneconomic after its selling price falls. What is the best explanation?
- Its economic availability changes; in the syllabus classification it may become conditional.
- It becomes speculative because all unused deposits are speculative.
- The geological evidence has disappeared.