Jerry Garcia’s legacy as a guitarist and singer with the Grateful Dead rightly will always be the first line in the bio.  Yet, GarciaLive, the ongoing series of releases detailing the musician’s live output away from the Dead, diligently and consistently has been adding import to the successive sentences of Garcia’s story.  With its 15th volume, the focus this time is on a rare gig nearly 50 years ago at a North Beach San Fran club, the Keystone Korner, as Jerry and pals Merl Saunders, Bill Vitt, and Martin Fierro burrow into the underground sound of San Francisco’s jazz scene.

Playing primarily as a trio, without usual suspect John Kahn helming the bass, and joined intermittently by Fierro’s sax, the three really explore the space.  There are songs, at least blueprints of, like “I Was Made To Love Her,” that stretch and flex the jam muscles, or the pensive “That’s All Right,” that provide Garcia an opportunity to sing a bit.  The joy, though, is more in the gateless expanse afforded them to just play and experiment freely throughout.  The “Keystone Korner Jam,” despite its casually tossed-off title, begins a 16-minute freak-out christened by a “Bertha”-like intro but just as quickly vapes into contemporaneous nods to Carlos Santana and Gabor Szabo.  Saunders, Vitt, and Fierro push for more and more from Jerry, and each other, and they get it.

If the music of the Grateful Dead was water Garcia waded into time and time again, often emerging with pans of gold, then Jerry the solo artist, away from that river, was just as eager to descend into the mine shaft in search of other precious metals.  Think of GarciaLive 15 as another bucket of lustrous, if unpolished silver; plenty valuable as both a standalone beauty and as a complement to its shinier counterpart.