Hi barb4777
Your description matches the
Metoprolol 25 mg pill exactly, but really the only way to double check is to have a look at the pill and see if it is the same.
There is an image on the manufacturer's website
Click on the link
http://www.mylanpharms.com/product_guide/
and then click on the link to Metoprolol Tartrate
Maybe it was something prescribed to your mother on a previous occasion and it didn't agree with her? Has she ever had chest pains?