Mississippi Valley type (MVT) Pb-Zn deposits are becoming the main supply of gallium and indium resources worldwide. In such deposits, sphalerite (ZnS) is the mineral variety that hosts these rare metals highly valuable in high-tech and energy transition. Understanding the deposit formation processes is of great importance to efficiently and sustainably exploit these rare metal deposits. In this proposal we wish to use μ-XRF mapping coupled to high-resolution μ-XANES/EXAFS at the In and Ga K-edges in order to, 1) identify the distribution these two metals in various sphalerite minerals showing different colors and formation stages in the deposit, 2) characterize the crystal chemistry of In and Ga in sphalerite (i.e., their speciation and substitution modes), 3) study their – potentially coupled – enrichment mechanisms in Pb-Zn deposits.