Nacre (mother of pearl) is an elaborate combination of aragonite, calcite, and protein. When the protein degenerates, the soft sheen disappears. Compare the aragonite shells with the calcite ...

Much attention had been also paid to their true mineral constitution, so as to ascertain in which groups the carbonate of lime exists in the form of calcite, and in which as aragonite. The results ...

Over the long term, as coral reefs continue to build themselves up, the framework of the coral reef is filled with sediment and cemented with calcite and aragonite. If sea level changes ...