Agates geodes are often cut and shaped into bookend sets or sliced and polished pair slabs or singles.
Agate is a form of
quartz having submicroscopic grains of cryptocryastaline quartz,
called chalcedony, in a massive form, often filling voids as veins or
geodes.
Agate is often found with color bands due to impurities in
the fluids from which the agate is deposited. Agate is usually
translucent, sometimes transparent, and has a hardness of 7, but has
no crystal structure (amorphous).