black scale
n.— «The pentatonic scale is sometimes called the black scale, as so many Negro spirituals are pentatonic: “Swing Low, Sweet Chariot” and “Deep River” were named. (I happen to know that Wings’”Mull of Kintyre” is also pentatonic, but that wasn’t mentioned.) The definitive version is Mahalia Jackson’s.» —“Tears of redemption, snorts of derision” by Miranda Sawyer Observer (United Kingdom) Mar. 25, 2007. (source: Double-Tongued Dictionary)