
1) American pottery 2) British pottery
Found on
https://www.crosswordclues.com/clue/ironstone-china

Ironstone china, ironstone ware or most commonly just ironstone, is a type of vitreous pottery first made in the United Kingdom in late 18th-century. It is often classed as earthenware although in appearance and properties it is similar to fine stoneware. It was developed in the 19th century by potters in Staffordshire, England as a cheaper, mass-...
Found on
http://en.wikipedia.org/wiki/Ironstone_china

type of stoneware introduced in England early in the 19th century by Staffordshire potters who sought to develop a porcelain substitute that could ... [2 related articles]
Found on
http://www.britannica.com/eb/a-z/i/40

See stone china.
Found on
http://www.encyclo.co.uk/visitor-contributions.php

A non translucent but very hard dense body in vogue in the nineteenth century. Mason’s Ironstone China is the best known but there were many varieties. Much experiment was done with hard white earthenware bodies at the beginning of the nineteenth century and these are often difficult to categorise.
Found on
https://ashbrook-ceramics.co.uk/pottery-glossary/
No exact match found.