Volcanic rock can come in a wide range of colors, depending on the minerals it contains and how it cooled. Here are some common colors and the minerals that give them:

* Black or dark gray: Common in basalt, a rock rich in magnesium and iron.

* Red or brown: Iron oxide minerals like hematite and goethite give these colors, often seen in rocks that have been exposed to weathering.

* Green: Olivine, a common mineral in volcanic rocks, can give a green hue.

* White or light gray: Feldspar minerals, like albite, can give a light color.

* Yellow or orange: Sulfur deposits, often found near volcanic vents, can give a yellow or orange color.

It's important to note that the color of volcanic rock is just one factor in identifying it. Other characteristics, like texture, mineral composition, and density, are also important.