Hardstone

Hardstone is a non-scientific term, mostly encountered in the decorative arts or archaeology, that has a similar meaning to semi-precious stones, or gemstones.

Two-dimensional inlay techniques for floors, furniture and walls include pietre dure, opus sectile (Ancient Roman), and medieval Cosmatesque work – these typically inlay hardstone pieces into a background of marble or some other building stone.

The definition of "hardstone" is not very rigid, but excludes "soft" stones such as soapstone (steatite) and minerals such as alabaster, both widely used for carving.

On the Mohs scale of mineral hardness, quartz rates no higher than a 7, less for types with impurities.

Stones typically used for buildings and large sculpture are not often used for small objects such as vessels, although this does occur.