There are provided a pearl culture material containing at least one selected from the group consisting of a pearl nucleus and a mantle, and the at least one selected from the group consisting of a pearl nucleus and a mantle contains a protein having 10 EU/g or less of an endotoxin amount, a nucleus insertion method, and a pearl culture material composition.

There are provided a pearl culture material containing at least one selected from the group consisting of a pearl nucleus and a mantle, and the at least one selected from the group consisting of a pearl nucleus and a mantle contains a protein having 10 EU/g or less of an endotoxin amount, a nucleus insertion method, and a pearl culture material composition.

There are provided a pearl culture material containing at least one selected from the group consisting of a pearl nucleus and a mantle, and the at least one selected from the group consisting of a pearl nucleus and a mantle contains a protein having 10 EU/g or less of an endotoxin amount, a nucleus insertion method, and a pearl culture material composition.

Provided is a method for producing a calcium carbonate sintered compact by which sintering can be done at a lower temperature and a higher-density calcium carbonate sintered compact can be produced. A method for producing a calcium carbonate sintered compact includes the steps of: preparing calcium carbonate and a sintering aid that is a mixture of potassium fluoride, lithium fluoride, and sodium fluoride and has a melting point of 600 C. or less; compression molding a mixture of the calcium carbonate and the sintering aid mixed to contain the sintering aid in an amount of 0.1 to 3.0% by mass, thus making a green compact; and sintering the green compact to produce a calcium carbonate sintered compact.

Provided are a pearl culture material in which at least one selected from the group consisting of a pearl nucleus and a mantle piece is coated with a protein containing a repeating sequence of GXY triplets which may be separated by one or more amino acids, and one or more RGD motifs, and having a polydispersity of less than 20; and a coating composition including the protein.

Provided are a pearl culture material in which at least one selected from the group consisting of a pearl nucleus and a mantle piece is coated with a protein containing a repeating sequence of GXY triplets which may be separated by one or more amino acids, and one or more RGD motifs, and having a polydispersity of less than 20; and a coating composition including the protein.