Conch shell

The conch shell, which is 99% calcium carbonate, is therefore really a composite material in which proteins provide the toughness that makes the shell so resistant to shattering. Although the conch shell itself is not useful (except to the conch), it illustrates how composites may offer much greater strength than the individual substances involved. Lessons learned from the conch... 

The baler, Mdb meHo, and other molluscs of the same genus, are also gastropods and can also produce pearls. The baler shell is orange inside and has the same flame pattern as a conch shell. The pearls can vary in size, some being quite large. They display the same colouring and flame pattern as the shell. 

Viewed with a lOx lens, non-nacreous shell displays a structure of faint striations. The orientation of the striations in each layer of colour is approximately perpendicular to the next layer. The exception to this rule is conch shell, which has striations in the same orientation (Figs 10.21 and 10.22). 

Conch shell fades with exposure to light. This can result in an item that is pure white and has striations running in the same direction. In small items such as beads, this can resemble white coral. When viewed from various angles the structure of coral becomes apparent. 

Figure 10.21 Detail of sli tly feded conch shell cameo, ahowii stiiations ruimii in the same diiecuon.

Early on, conch shells brought back to Europe had been ground down and used as a component of porcelain. As the shell carving industry evolved, various centres for the craft developed. The most famous centre is Torre del Greco near Naples in Italy, where shells are still made into cameos, and coral is still carved. 

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