Sassanian Coin [solved]

A coin of which I know virtually nothing except recognition by its style. Trust there is enough left to attribute.

D.- 28mm
W.- 3.59 grams
Metal- Silver

Yes, somewhat difficult because of the condition of the coin. I'm not certain, but using the excellent guide to Sasanian coins at

http://beastcoins.com/Sasanian/Sasanian.htm

it looks to me like a good match for Khusro I (531-579 AD). My guess as to the mintmark is GD (city known as Gay or Jayy). With the coin in hand perhaps you can better compare with the images on this website.
And hopefully someone more knowledgeable on this type of coin can confirm the identity and possibly read the regnal year.

Many thanks Seeker55. I think you have it right. In addition to Khusro I and the GD mintmark, the regnal year 29 is indicated by a message via private correspondence. After many years, It appears that this attribution is finally concluded.