part of the reason for this is that this is a volcanic island, and there are several big quarries that dig up granite and slice it up all day long

i remember seeing it on the road up from camacha central to the airbnb i rented when i first arrived, loads of sliced shards of fancy stone just laying around

that's partly why in portugal in general, it is very common to see pavements and driveways composed out of shattered shards of fancy granitic rock slivers, it's pretty wild, but i think most of it comes from these volcanic islands