These slices were cut from a single crystal of liddicoatite, a member of the tourmaline family. They reveal the crystal's history, just as the rings in a tree record its past. Crystals may start and stop growing many times. In most cases, there's no way of knowing how long each phase lasted.

Why the Different Colors? This crystal changed color as it grew.

• The purple portion of the liddicoatite formed when the solution feeding it was manganese-rich.

• The yellow part grew when the solution became iron-rich.