Can a rock be considered frozen Water usually comes to mind when thinking about freezing. Once it reaches a certain temperature, water freezes, becoming a solid.
However could you make the same statement about a rock? Is a rock at room temperature considered frozen because it is in a solid state?
 A: Yes, rocks are solids, though not all of them will have frozen and there's a minor complication about what we mean by freezing for some rocks.
Firstly note that sedimentary rocks formed by chemical processes so they were never liquid. So although these rocks are solid, they haven't frozen. In fact you can't even melt carbonate based rock because it decomposes (to calcium oxide) before it melts, so if you take limestone and melt then freeze it you end up with a different rock.
However the vast majority or rock in the crust is frozen magma formed at mid ocean rifts or volcanos and this has indeed been frozen when the originally molten lava cooled and solidified. Note that rock tends to be a mixture of different chemicals so it doesn't all freeze at once. You get crystals of different materials forming in sequence as the lave cools.
I did mention a minor complication, and that's because some rocks are amorphous like glass. An example would be obsidian. Amorphous materials go through a glass transition that is for most common purposes the same as freezing, but has subtleties that distinguish it from the usual liquid-solid transition.
A: What you have to understand is that starting from nuclei and electrons there are the so called phases of matter.


This diagram illustrates transitions between the four fundamental states of matter

All matter microscopically  depends on the mobility of its constituents, as it is thermodynamically measured by enthalpy, 

a measure of the total energy of a thermodynamic system

Thus all solids are "frozen" which is the state reached when the energy of the system is low enough. Magma is the liquid state of rocks around a volcano, for example.
An interesting diagram  that applies to all matter is this:


A typical phase diagram. The dotted line gives the anomalous behavior of water.

which shows the temperature versus pressure reactions of matter and how they transition from one state to the other depending on these variables.
