Nacre

The shell of the rayed-ridged mussel contains over 90% calcium carbonate and about 0.34% organic matter; it also contains a small amount of magnesium, iron, silicate, sulfate, phosphate, and chloride. After calcination, the carbonate decomposes to produce calcium oxide and the like, while the organic matter is destroyed.

After administering the nacreous-layer powder of Pteria martensii to rabbits, the blood calcium ion concentration is almost the same as after calcium carbonate administration; its 30% sulfuric-acid hydrolysate contains amino acids such as leucine, methionine, alanine, glycine, and glutamic acid; it has no effect on rabbit ear-shell blood vessels or blood pressure, but increases the amplitude of the isolated toad heart beat, reduces the tension of the isolated rabbit intestine, and has a transient diuretic effect in rabbits.

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