Where do the mini-aetherytes come from?

[ElHeggunte]

In the patch notes:

Furnishing makes me think it's craftable, but I don't see it in any of the craft logs, nor on XIVDB. The new Savage Arc furnishing appears (GSM 2-star) though.

If the mini-aetheryte isn't craftable, how do you get it?

Seriously? It says it right there in the portion that you quoted. They're a Grand Company reward you can purchase for 14,470 seals at the Second Lieutenant rank.