Dave Pickerell, the master distiller who joined forces with Metallica to create their signature Blackened Whiskey blend just a few short months ago, passed away unexpectedly on Thursday morning. Pickerell was in San Francisco for the annual WhiskyFest event at the time of his death, which was confirmed by WhistlePig Whiskey. The cause of Pickerell's death has yet to be announced.

Metallica took to Twitter to share their condolences: "The Metallica family is stunned and in disbelief at the loss of our friend and partner, Dave Pickerell. He was not only a mentor and friend, we considered him a member of Metallica. We learned so much from Dave in the all too brief time we had together. But more than anything, Dave was our good friend and we will miss him tremendously. In his passion for his craft, we found a truly kindred soul - Dave lived to see people enjoy what he created, and we enjoyed every minute of our collaboration on our Blackened Whiskey with him. And judging by the smile on his face whenever we were together, we think the feeling was mutual. Rest In Peace, Dave."

After a 14-year tenure with Kentucky bourbon company Maker's Mark, Pickerell left to run his own consulting company and split time between WhistlePig Whiskey in Vermont, Hillrock in Ancram, New York, and the old-fashioned distillery at the Mount Vernon plantation formerly owned by George Washington.

WhistlePig Whiskey also paid tribute on social media, posting on Facebook this morning, "Yesterday we lost a friend, father, and luminary to the world of whiskey. Our heavy hearts and raised glasses are with Dave's friends and the entire Pickerell family as we all mourn the loss of a legend."

Read a moving tribute by friend and fellow whiskey expert Noah Rothbaum published earlier today here.