Gofun is an opaque white pigment made from pulverized high quality oyster shells. It has a pearl like luster. Used in traditional japanese doll making, and also often splashed on a print to imitate effects such as snow in a three dimensional manner.
It is made from natural clam shell, by allowing Oyster shells to decompose until all organic matter is gone then grinding the remaining shell. Nowadays there is only one or two traditional manufacturer left doing this.