Article continues below advertisementKelly Clarkson's ex-husband Brandon Blackstock's cause of death has been revealed less than a week after the talent agent passed away at age 48.Blackstock's cause of death was melanoma, a form of skin cancer, with the manner of death ruled as natural causes. "Brandon Blackstock passed away peacefully at his home in Butte, Montana on August 7th under hospice care surrounded by his family," Silver Bow County Coroner Dan Hollis confirmed to a news outlet on Monday, August 11.