Old Emerald/Glass Broach/Necklace?

This was dug up in the family garden about 30 yrs or so ago (north Alabama).  No one knows it's history or anything (all I know is that some of my family were German immigrants).  It is has no markings.  The "carving" may be a  god/goddess or ?   The carving is so detailed!   The metal is fairly simple in design, but very strong. The edges look like they are "pinched", so, it appears hand-made.    Cannot tell what kind of metal; but, the back has lots of "scrape marks", like the metal was sliced off a slab or something; and metal is still shiny on the back.  

Can anyone help with:

~ an idea of AGE?  

~if it is EMERALD OR GLASS,  OR?

~WHO/WHAT is the CARVING?

~WHAT KIND OF METAL?   (there appears to be a piece broken off on the top; maybe the hole for a chain or ? for a necklace?)

~ BROACH or NECKLACE or TYPE of jewelry? 

~WHERE could it have came from,  COUNTRY OF ORIGIN?  

~  WORTH?   

THANKS for any help!!