James,
I've not seen this one before ...
The green/white shield leads me to believe Saxony as a regional indicator? I don't believe I've ever seen such diminutive roundels on a military emblem or bullion insignia, so I'd agree with you that it's civilian in nature.
The main figure of the Wappen looks like a railroad logo briefly and then again, not.
And the initials, "St A M K" are unfamiliar, too? Rather than a school, I'd say an organization of some kind, like a club or fraternal order? Difficult at best ...
Hopefully some of our other friends will be able to add some more thoughts on this one.
Thanks for sharing!
Bill