Conch Clues

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 

A third type of solid is illustrated by elements such as graphite, diamond, and buckminsterfullerene (all pure carbon), boron, silicon, and all metals. 

Examples of three types of crystalline solids. Only part of the structure is shown in each case, (a) An atomic solid, (b) An ionic solid, (c) A molecular solid. The dashed lines show the hydrogen bonding among the polar water molecules. 

The internal forces in a solid determine the properties of the solid. 

These substances all have atoms occupying the lattice points we wi ca t em atomic solids. Examples of the three types of solids are shown in Fig.  

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