Uranus is not mostly made of gas, although it's classified as a gas giant. It's more accurate to say that it's composed of icy material and rock.

Here's a breakdown:

* Ice: This includes water, methane, and ammonia, which are frozen at Uranus's extremely low temperatures. These "ices" make up the majority of Uranus's mass.

* Rock: A small, dense rocky core lies at Uranus's center.

The reason Uranus is called a gas giant is that its atmosphere is composed mainly of hydrogen and helium, just like other gas giants like Jupiter and Saturn. However, this atmosphere is only a thin layer compared to the planet's overall composition.

So, while Uranus has a gaseous atmosphere, it's primarily composed of ices and rock, making it more of an "ice giant" than a gas giant.