Rock-derived nutrients such as calcium (Ca), magnesium (Mg), phosphorus (P), and potassium (K) are essential plant resources, yet depleted in highly weathered tropical soils, leading to nutrient limitation of productivity or other ecosystem processes. Despite this, substantial amounts of rock-derived nutrients occur within wood, which raises questions about the role that wood nutrients play in the ecology of tropical forests. Using data from forests across the tropics, we quantify wood nutrient stocks at individual tree and ecosystem levels. At the ecosystem level, we show that tropical wood can store substantial amounts of rock-derived nutrients. Furthermore, on a tree level, tree species vary widely in woody nutrient concentrations. These observations raise important questions as to the biogeochemical or ecological drivers that lead to this variability, as well as the role that woody tissue plays in the buffering and cycling of nutrients. We offer some potential explanations and direction for future research to explore this under-appreciated but sizable store of inorganic nutrients in tropical biomass.