The rock cycle
Igneous → sedimentary → metamorphic. Stone is a process, not a thing.
Stone is not a thing — it's a loop. Igneous rock cools from magma, weathers into sediment, buries into sedimentary rock, and bakes into metamorphic rock, which can melt and start again.
The loop
igneous magma cools (granite, basalt) sedimentary sediment compacts (sandstone, limestone) metamorphic heat + pressure recooks (marble, quartzite) all three can melt and become magma again
Why it matters
Every slab in your kitchen is a snapshot of one moment in this loop. The granite was once liquid, the marble was once a seabed, and both are on their way to being something else. Stone is just time, briefly solid.