Pentagram has posted the following sad news on their official Facebook page:

"We're saddened to learn of the passing of Stuart Rose, drummer for Pentagram in the mid ‘80s. Stuart came on board in the midst of the name change from Death Row to Pentagram in 1984. His one full-length release with the band was the 1987 album Day of Reckoning, which would eventually become monumental in regards to the history and evolution of doom metal. Stuart was really happy to have both audio and visual of his playing finally surface properly on the Pentagram DVD collection, All Your Sins, in 2015. Among the cherished footage is his '84 performance with the band at the historic CBGBs in NYC. Stuart was a talented drummer, a clever and funny guy, and he will be missed. We offer our utmost condolences and prayers to his family during this time. Godspeed."

From Wikipedia regarding Day Of Reckoning and Rose's contributions:

Day of Reckoning is the second album by Pentagram. It was released in 1987 by Napalm Records. It was re-released by Peaceville Records in 1993, and in 1996 as part of a two-disc split CD with Relentless, and then again in 2005 as a digipak CD. Joe Hasselvander originally played drums on only one track, "Burning Savior," with Stuart Rose recording the drums on all the rest. Hasselvander re-recorded drums on all tracks (except "Burning Savior") for the 1993 Peaceville reissue.The original mixes with Rose on drums only appear on the Napalm Records LP version and an original cassette edition made in Canada, and have never appeared on CD.