What stone milling means
Traditional matcha is milled on a granite ishiusu, a paired stone wheel that turns at roughly 30 to 60 rotations per minute and produces only about 30 to 40 grams of powder per hour. The slow speed keeps the leaf cool, which preserves color and aroma. Producers such as Ippodo and Marukyu Koyamaen still use stone mills for top blends, while higher-volume tins are sometimes finished on ceramic or air-jet mills.
Also called
Stone milling also appears as ishiusu milling.