Our understanding of supply and demand conflicts of critical minerals is quite limited, which may inhibit strategies in their criticality mitigation. This is particularly severe for gadolinium (Gd), as a heavy rare earth element, given its small amounts in supply and wide applications ranging from glass to NdFeB magnets. This study (1) developed a sophisticated accounting framework to measure the supply and demand trends of Gd within China from 1990 to 2018 and (2) provided a qualitative review and discussions on Gd supply-demand balance in a holistic perspective. Our findings suggest that the balance of Gd supply and demand shows a cyclical trend, termed as periodic "scarcity-abundance" pattern, influenced by changes in environmental regulations, trade structures, and technological applications. This highlights the importance of the joint measurement of both supply and demand of critical minerals for their criticality mitigation.