胡粉

ごふん

胡粉 is the calcium-carbonate shell white that gives 胡粉色 its name and is still made for nihonga today.

Tobunken's 彩色DB records 胡粉 (shell white) in Nara-period inventories such as the Hōryū-ji records.

Material context only; whiteness depends on shell source and grind, so the HEX stays an approximation.