Some, but not all, agates contain “vugs,” tiny voids often filled with quartz crystals.  They are a sort of miniature geode.  The crystals when present are usually very petite (sometimes microscopic).

Note that two of the three vugs pictured in the image below have visible quartz crystals.  Some lapidists view vugs as imperfections to be avoided when cutting a stone.  I, however, love to include vugs when cutting cabochon. I like to see the sparkle that often emanates from the vug when a tiny crystal catches a ray of light.

Including a vug in a cab adds beauty, uniqueness, and perhaps, as some believe, mystical powers.  I do not know the technical name for the type of agate shown. In fact, many agate types are unnamed or have local names which have been applied to them.  If you would like to name this type of agate, let me know what you think.

I am an unknown agate. Name me!