huntite

Ingredients

huntite, whewellite

Preparation Steps

Original Recipe Text

The white paint was predominantly used for whitening a clay-straw plaster (p. 218). The paint is composed of huntite (CaMg3(CO3)4), which is documented to be used in central Iran, particularly in the Yazd province where deposits are abundant (p. 220). Analysis identified the presence of hydrated calcium oxalate (whewellite) within the mixture, likely formed via the chemical reaction of degrading natural binders with the white huntite (p. 221).

Evidence

"The Raman bands centred at 252, 271, 316, 726, 746, 879 and 1123 cm−1 established white huntite (CaMg3(CO3)4) as the main constituent of the white paint (Fig. 3a)."

Remarks

Huntite is known by several names in Iran, including 'gil-i sifid', 'gil-i guiva', and 'gil-i yazdi', meaning 'white paste' or 'paste of Yazd' (p. 220). The presence of whewellite is a marker of original organic material as a binder, possibly proteinaceous, which degraded via micro-organisms and reacted with the huntite to form calcium and magnesium oxalates (p. 221).