Here's why:

* Mineral Composition: Granite is primarily composed of quartz and feldspar, both of which are very hard minerals. Basalt is primarily made up of plagioclase feldspar and pyroxene, which are less hard than quartz.

* Mohs Hardness Scale: On the Mohs Hardness Scale, quartz has a hardness of 7, feldspar around 6, and pyroxene around 5-6. This means quartz can scratch feldspar and pyroxene, indicating it is harder.

* Crystal Structure: The interlocking crystal structure of granite contributes to its overall hardness. Basalt has a more porous and less tightly packed structure.

While basalt is harder than many other rocks, granite's mineral composition and structure make it significantly more resistant to scratching and abrasion.