What is this cartridge?

So basically, it looks to be one of the first MC cartridges.

First MONO MC invented by Ortofon (Denmak)
First Stereo MC invented by Grado (USA)

Grado timeline here 

Interesting! Thanks!

LOL! Beat me to it. I spent too long reading those pages. So basically, it looks to be one of the first MC cartridges.

It look like this and very similar to this Grado cartridge 

  Brooklyn-born Joseph Grado attended a trade school, but he dropped out at 17 to join the Navy. He studied watch making at vocational school and after the Navy was able to secure a position at Tiffany’s & Company. In 1948 he started his own watch repair shop but continued to work for Tiffany. In the early 50s Grado discovered the newly evolving high-fidelity industry. In 1950 he went to work for Fairchild Recording Equipment Company to resolve production issues with their phono cartridge. HiFi ultimately became Joe’s lifetime passion and he started building monaural phono cartridges by hand at home in Brooklyn. 

So that early Grado cartridge is very similar to a Fairchild Cartridge.