This is the first I've heard of a harmonium, although it's immediately obvious to me that I've listened to it before. I have to admit it doesn't sound at all like an Indian instrument to my Western ears. Perhaps I've been spoiled by the sitar and flute, as played by the likes of Ravi Shankar and Paul Horn, with beautifully fluid transitions between notes, but the harmonium seems oddly rigid and tonally out of place in my concept of Indian classical, unless it were relegated to use as a drone (which it would do wonderfully).
It isn't strictly speaking an Indian instrument, Indians picked it up from western Christian missionaries who loved reed organs. They adapted it to Indian musical tastes though.
The harmonium is very uncommon in western popular music. Nico’s early albums from the 70’s feature it prominently, that’s the highest-profile example I can think of. Desertshore is a favorite.
