I'm not sure if this ore is meant to be spawning. It appears to have started spawning in new chunks since we updated to 1.1.

It was first noticed in a Badlands-esque higher level Mineshafts overlapping into a desert biome, and in a "Caves" biome beneath:

Specifically the ores that are spawning are from LibVulpes that are not listed in JEI, break into the ore block and don't have any processing method, and primarily include:

• libvulpes:oredilithium
• libvulpes:orealuminum

It spawns extensively underground beneath deserts:

I was going to search more extensively in the surrounding area to see if they spawn outside of these biomes but unfortunately my client just crashed...

Okay, it's spawning in the caves beneath the nearby Savanna:

As well as under an ocean:

Closer to home in the original chunks generated in the 1.0 version, it doesn't seem to spawn at all:

It does seem to spawn very extensively.

So the answer here appears to be that my server config was considered "invalid" and replaced by default configurations at some point during the upgrade from 1.0 to 1.1.