diorite
A coarse-grained igneous rock consisting primarily of plagioclase feldspar, pyroxene, and hornblende, typically appearing salt-and-pepper in color.
Noun
Diorite is a technical geological term used primarily in scientific, archaeological, and architectural contexts. It is characterized by its extreme hardness and durability, which made it a preferred material for royal sculptures and monuments in ancient Egypt and Mesopotamia.
Because it is a specific type of rock, it is treated as a mass noun when referring to the material itself. While it can be pluralized in a technical geological sense to describe different types or samples of the rock, in general usage it remains uncountable.