Agate flat square bead-link necklace

I don't know what type of agate this is except for "fairly gray".  Anyway, each bead measures 12x12mm, & is linked with tarnish resistant silver-plated wire.  The clasp is a silver-plated hook & eye.
The length is 25.75 inches (can be worn shorter by hooking the hook between two beads)and the weight is 2.1 oz.

Price: $17.70 (shipping is free)