Basalt is typically dark gray to black, but can also be found in shades of brown, green, or even purple.

Here's why:

* Composition: Basalt is a volcanic rock made of dark-colored minerals like pyroxene, olivine, and plagioclase feldspar. These minerals give basalt its characteristic dark hue.

* Weathering: Over time, basalt can weather and oxidize, giving it a brown or reddish tint.

* Trace Elements: The presence of certain trace elements, like iron oxides, can influence the color of basalt. For example, iron oxides can make basalt appear reddish or purple.

So while the most common color for basalt is dark gray to black, it can also be found in a variety of other shades depending on its composition and weathering.