Diorite

Diorite is a stone-like material.

Polished Diorite is the polished version of diorite. As with granite and andesite, it can be crafted from regular diorite.

Naturally generated
Regular diorite generates anywhere underground in rich seams, in an identical way to the other two stone types, as well as gravel and underground dirt. It is most commonly exposed to the surface in Extreme Hills biomes but can also be found commonly in other biomes.

Crafting
Polished diorite can also be crafted from regular diorite, see below.