Here's why:

* Streak color is determined by rubbing a mineral against a streak plate (unglazed porcelain). The color of the powder left behind is the streak.

* Granite is an igneous rock, meaning it's formed from cooled magma. It's a mixture of different minerals like quartz, feldspar, mica, and others.

* Streak tests are primarily used to identify minerals, not rocks.

So, while individual minerals in granite might have streak colors, granite as a whole doesn't have a single streak color.