Japanese white pigments before modern times fall into three groups: white clays, white compounds of lead, and oyster-shell white (calcium carbonate). White-clay pigments were commonly used up to the 15th or 16th centuries and show some variation of composition, perhaps corresponding to geographical origin. Lead-based white pigments were long assumed to correspond to basic lead carbonate or lead-white . Recent work at the Freer Gallery of Art has shown that basic lead chloride is also frequently found. Around the 15-16th centuries, white clays were entirely displaced, and lead compounds partly displaced, by a calcium carbonate white made from pulverized oyster shells. calcium carbonate white made from pulverized oyster shells.