Black Sabbath's "Vol. 4" isn't heavy metal
As with Black Sabbath's first three classic albums, the age-old consensus that 1972's "Vol 4" is a "heavy metal" record doesn't stack up to closer scrutiny, at least not when you take into account the modern metal genre tree. If the album was released today as the debut release from a new band then I feel confident that it'd be tagged as a stoner metal record which is in line with my long-term feeling that it doesn't sit all that comfortably alongside your Judas Priests & Iron Maidens.
For the record, this is how I've tagged the album:
01. Wheels of Confusion - Heavy psych
02. Tomorrow's Dream - Stoner metal
03. Changes - Piano rock
04. FX - Experimental
05. Supernaut - Stoner rock
06. Snowblind - Stoner metal
07. Cornucopia - Stoner metal
08. Laguna Sunrise - Chamber folk
09. St. Vitus Dance - Stoner rock
10. Under The Sun - Stoner metal
As you can see, more than 50% of the tracklisting falls outside of the metal space however the stoner rock & heavy psych inclusions are also closely aligned with the stoner metal tag & there is enough genuine metal to qualify for the Academy anyway. Given that we've recently voted to have "Vol 4" added to The Fallen under the Stoner Metal genre, I'd like to see it removed from The Guardians & the Heavy Metal genre so that it resides solely in The Fallen under Stoner Metal.
https://metal.academy/hall/506