| 1. This paper is an electron microscope study of the alterations produced by temperatures in range of 100°C to 900°C in mother-of-pearl of the modern <i>Nautilus</i> shell. 2. Fragments of nacreous layers of the shell wall in the living chamber were exposed for 5 minutes to 21 days to dry heat in open vessels and in quartz tubes sealed under vacuum or argon. Other fragments were boiled in sea mud and sea water. 3. In open vessels and in sealed tubes, conversion of aragonite into calcite took place in the samples heated at 400 °C and above. In the 600 °C-900 °C samples, calcite was mixed with varying amounts of calcium oxide. With elevation of temperature, the original hard, compact and stratified mother-of-pearl became progressively brittle,... |
