What are the dark rocks in the monzogranite? https://geologyistheway.com/blog/2022/0 ... drea-elba/ This person takes the long way to explain but I like some of the illustrations (i.e. using a lava lamp for those of us that remember them): The rocks that are dark-colored, they are fine-grained with respect to the surrounding granite, and they are included in the granite… hence they are called – with no much imagination – mafic microgranular enclaves or simply mafic enclaves. Moreover, beyond the features listed above, mafic enclaves always show this rounded outline.

The structures that we see here witness the constant process of interaction and evolution of different magmas that constantly occurs beneath our feet. When lava comes out of volcanoes, these processes have already happened. Hence, studying exhumed intrusions is an excellent way to understand how magma migrates and evolves into different compositions before eruptions.