Mort Garson "Black Mass/ Lucifer" (UNI, 73111, 1971)
A great proto-prog (okay, okay -- I'm really just making terms up now) Moog album from 1971 that's been fairly well documented elsewhere on the web, this was the brainchild of Mr. Mort Garson, working under the conceptual name of "Lucifer". While I know it's mostly just hard to imagine a major label running with something this "out there" today (making it an excellent companion to Louise Huebner's "Seduction Through Witchcraft" LP from 1969), the real surprise for a lot of the folks I've played it for is the compositional tightness of the songs, and how enjoyably it all works as a whole. Not just a cultural artifact from the early 70's, it's got some genuine creepiness to it as well that could easily be seen as pre-figuring a lot of the sounds Goblin would employ only a few years later.
Note: As a bonus for folks who may already have this in their collection I've also included scans of the complete liner notes in with the zip file. Written by Michael Owen Jones Ph.D. (still a professor of History and Folklore at UCLA), they never seem to make the rounds when this record is shared, which is a shame as they're almost half the fun.