This is an antique Victorian or Edwardian square shape faceted open salt, salt dip or salt cellarin clear glass made 1890-1910.

The open salt measures .75 of an inch high by just over 1 inch square with mildly tapering sies, beveled rim and optic base..

The optic open salt has quire a few fleabite chips on the facets, so has seen quite a bit of use in it's long life, and I would call it in good +++ used antique condition with great patina.

The optic square open salt is listed in the book 5,000 Open Salts; A Collector's Guide by Heacock and Johnson.

So useful for so many things, and a very fancy teabag holder at your tea table!