Gold is generally resilient but if it’s in the form of tiny particles, it suffers negatively from heat, pressure, corrosion, oxidation and other conditions.
Nickelates may be crucial for high-temperature superconductors that are much easier to cool and thus are far more promising for potential future applications.
Coal deposits are known to be a potential source of REEs, and work is underway in the US and elsewhere to separate and concentrate REEs during coal processing