Here's why:

* Composition: Granite is made up of quartz, feldspar, and mica, all of which are very resistant to chemical weathering.

* Hard and Crystalline: Granite is a hard and crystalline rock, making it difficult for physical weathering processes like abrasion to break it down.

* Low Porosity: Granite has a low porosity, meaning it doesn't have many spaces for water to penetrate and cause chemical weathering.

While granite may weather slowly, it's not completely immune to erosion. Over long periods of time, even the hardest rocks can be broken down by weathering and erosion.