Some gems come from plants
and animals. Pearls are gems
made by oysters. How?
Sand and other material get
inside the shell. The materials
are coated with a special
substance. Finally, a pearl
forms. Clams and other
shellfish make pearls, too.
Jet is
fossilized
wood. It is
formed when a piece of
wood washes into water.
It sinks to the bottom. It gets covered
by
sediment
. Over time it is compacted
and transforms into a gem.
