Aluminum Oxide mineral is a versatile and durable mineral often used for quick cut rate and long life. Garnet mineral is a softer, less aggressive mineral as compared to it's aluminum oxide counterparts and is designed for final sanding on wood. Silicon Carbide mineral is used when a finer finish is needed. This mineral fractures easily constantly providing a high cut rate and fine consistent finish. Cubitron II is 3M's precision shaped grain; it offers top of the line cut rate and abrasive life.