Metamorphic rock Garden
These are formed by subjecting any kind of rock to high pressures and/or temperatures but without actually melting them. This changes the initial mineralogy and structure of the rock and produces a new rock.
Slate chips are used as a popular mulch for gardens.
Igneous Rock Garden
Magma is the molten or semi-molten natural material from which all igneous rocks are formed.
Once the magma has reached the surface of the volcano to create lava it cools and solidifies, it forms a type of igneous rock called basalt.