Well, more accurately, water is a lava, a magma when it's underground. In some parts of the Earth - in some times in Earth's history and destiny quite a lot of it - as in much of the rest of the universe, H2O is a kind of a rock. Water is thus molten rock - lava.
A geyser is literally a volcano.
In addition, geology divides rocks into basically three main classess: Igneous, sedimentary and metamorphic. Igneous rocks are rocks formed from frozen lava or magma. Rocks that form by pre-existing rock particles that get smashed or cemented together are sedimentary; rocks that get smashed together with so much intensity that they actually change their chemical structure are metamorphic. But if you think about it, all of the earth was molten once. All the rocks that form from lava that freezes are igneous rocks. The pre-existing material constituting sedimentary and metamorphic rocks are igneous rocks.
Thus, all rock is igneous rock.
Ice is also igneous rock, as water is lava. Thus, all the mineral part of Earth is Lava and the igneous rocks formed from it.
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