Australia is endowed with a wide range of critical minerals deposits, such as pegmatite-hosted Li and carbonatite-hosted rare-earth element (REE) deposits. However, a lack of understanding about host and gangue minerals in the respective mineral deposits is limiting the minerals industry from extracting the full value and potentially even stifling investment due to overpromised quality of the respective critical mineral deposits. This is where mineralogy becomes critical. In the case of pegmatite-hosted Li, a recent comparison of six different pegmatite-hosted Li deposits from across Australia shows that Greenbushes is unique, most notably in regard to: 1) the comparably high amount of spodumene in respect to the gangue minerals; and 2) minor abundance of other Li-bearing mineral phases, such as petalite, eucryptite and montebrasite, which were identified in other case study sites. Li hosted in other minerals than spodumene significantly reduces the amount of recoverable Li, reducing the economic viability of an ore deposit. Furthermore, some Li-bearing pegmatites contain significant amounts of Fe-rich white mica, which are more disruptive than pure muscovite because their breakdown produces Fe-bearing melts and oxides that can modify slag or reaction products and potentially contaminate lithium concentrates. Accurate characterisation of host and gangue mineralogy is also important for extracting value from other critical minerals deposits, such as carbonatite- or clay-hosted REE deposits. Recent work by CSIRO Mineral Resources has shown that rapid analytical techniques, such as hyperspectral drill core logging, can be used to identify Nd-host mineral groups, such as phosphates or carbonates. This paper aims to put a spotlight on the complexities and opportunities associated with Li and REE mineral deposits in Australia. For this, mineralogical and geochemical results of example case studies are presented (Laukamp et al, 2026a, 2026b). Methods for rapid analysis of critical minerals are discussed, that support decision-making by mineral explorers, mineral processing engineers and downstream industry.