Dense metals is a mod responsible for generating a variant for each of the mineral resource blocks generated in the world. This new variant is a block where more minerals are concentrated than in the predefined blocks. That is, when mining one of these blocks, we will get more minerals than when mining a normal block.
Dense or concentrated blocks of Mineral Resources will appear around a Mineral Resource vein. For example, if we find a vein of iron, it is likely that around it we will find a concentrated block of this same mineral resource. Which means we can find more minerals in a mineral vein.