There are several factors that may cause a mineral deposit that had not been considered valuable to become highly sought after. Some of these factors include:
Technological advancements: Advances in technology can make it possible to extract and process minerals that were previously uneconomic. For example, if new technologies make it possible to extract a mineral from a previously unprofitable deposit, it can become highly sought after.
Market demand: Changes in market conditions can increase the demand for a particular mineral. For example, if a mineral is used in new technologies or products, the demand for it may increase, making previously uneconomic deposits viable.
Political or economic instability in a region can cause the prices of certain minerals to rise, making previously uneconomic deposits more attractive.
Exploration and discovery: New discoveries of mineral deposits can also lead to previously uneconomic deposits becoming highly sought after. Exploration companies and geologists are constantly searching for new mineral deposits, and when they find one, it can become highly sought after.
Natural occurrences: Natural occurrences such as natural disaster, geological shifts and changes in the environment can cause a previously uneconomic mineral deposit to become highly sought after.
It's important to note that these are just some examples, other factors may also play a role in the changes in the mineral market.