Hidden Treasures is a two-disc collection of previously unreleased material from the prodigiously talented Taj Mahal. The first disc features stripped-down outtakes from Mahal’s early studio sessions; the second is a rollicking live set that captures Mahal and his band performing at London’s Royal Albert Hall in 1970. All the material is exceptionally strong. The studio outtakes let listeners hear Taj work through more relaxed versions of songs that would eventually appear on his first four Columbia releases. He strolls through the blues classic “Good Morning Little Schoolgirl” with an offhand insouciance perfectly suited to the tune, and he displays his claw-hammer technique on “Shady Grove," an extended banjo workout that summons the spirit of old-time masters like Dock Boggs and Clarence Ashley. The live disc is equally rewarding, full of soulful, rousing performances that often eclipse their studio counterparts.