Mats (MP in French) means raw material. It can be drilling elements, cut up (lootted during a hunt) or OP mats (which arrive in the GH, when it has a Outpost).
Since Patch 00837 (December 2020) stars show if it's basic (no star), fine (1 star), choice (2 stars), excellent (3) or Supreme (4).
More on Crafting#Materials, Harvesting#Higher_Grade_Mats.
Last version 2022-05-25•ᐒ