Argentera granite

If you look closely at this grey rock, you will see that it is made of different minerals. Quartz (grey) and feldspar (white) sometimes big with a few sparkling areas here and there on the rock. This is black mica and more specifically biotite.
You have discovered blocks of granite. All the minerals it is made up of are contiguous and visible with the naked eye. The texture is igneous, characteristic of plutonic rocks which crystallised deep in the earth.