Bone ash is a white material produced by the calcination of bones. Typical bone ash consists of about 55.82% calcium oxide, 42.39% phosphorus pentoxide, and 1.79% water. The exact composition of these compounds varies depending upon the type of bones being used, but generally the formula for bone ash is: Ca5(OH)(PO4)3. Bone ash usually has a density around 3.10 g/mL and a melting point of 1670 °C (3038 °F). Most bones retain their cellular structure through calcination. History Bible From Isaiah: "And the people shall be as the burnings of lime: as thorns cut up shall they be burned in the fire" Its use is mentioned in the Book of Amos (2:1): "I will not turn away the punishment thereof, because he burned the bones of the King of Edom into lime." It was used in ancient formulas for white paint and cosmetic pigments, and in the cupellation process to separate silver from lead. Antiquity Burnt bones have been recovered from numerous Ancient Greek sanctuaries dating from the Late Bronze Age up to the Hellenistic period. The burnt bones are often calcined with a white or blueish color, allowing archaeologists to identify them as sacrificial remains. At the sanctuary to Artemis in Eretria a round altar of fieldstones filled with soil was found, dating to the 8th century BC. The upper surface was covered with clay and animal bones were burned on top, then apparently swept off the surface with terracotta, metal objects, and pottery and trampled until the altar was eventually subsumed by the ritual debris. Some scholars have attributed these altars to chthonian rituals, but this is disputed. Xenocrates of Aphrodisias reported its use as a medicinal ingredient, although cannibalism was, according to Galen, prohibited under the laws of the Roman Empire. Uses Bone china Bone ash is a key raw material for bone china. Constituting around 50% of the body, it reacts with other raw materials in the body during firing to form, amongst other phases, anorthite. In preparation for use in bone china, bones undergo multiple processing stages, including: Removal of any meat before being decreased. Calcination to around 1000 °C (1832 °F). This will remove all organic, and the bone is left sterilised. Ground with water to fine particle size. Partially dewatered. Since the 1990s, the use of synthetic alternatives to bone ash, which are based on dicalcium phosphate and tricalcium phosphate, has increased. Significant