What mineral can scratch feldspar and can be scratched by garnet?

The mineral that can scratch feldspar and can be scratched by garnet is quartz. Quartz has a hardness of 7 on the Mohs scale, making it capable of scratching feldspar, which has a hardness of 6. Meanwhile, garnet has a hardness of around 6.5 to 7.5, allowing it to scratch quartz but not all varieties of garnet will scratch quartz.