青あお砥と

noun

medium-grade millstone

Refers to a millstone of intermediate quality, used in traditional milling contexts. The term is relatively rare and may appear mainly in historical or technical discussions.

• 江え戸ど時じ代だいの資し料りょうには、青あお砥とと呼よばれる中ちゅう級きゅうの石いし臼うすが記き録ろくされている。

  Documents from the Edo period record medium-grade millstones called 青砥.