Marianna (Nancy) Langmuir died peacefully at her home in Santa Monica, Calif., alert and surrounded by her family. Mrs. Langmuir was 90 years old.

Born and raised in Englewood, N.J., she graduated from Vassar College with a degree in chemistry in 1939. After graduation, she went to work for Nelson Rockefeller as one of his personal secretaries when he was Coordinator of Inter-American Affairs in Washington DC, a post she held until 1945. In 1942 she married David Langmuir, a family friend whom she had know since childhood. They remained happily married for more than 60 years until his death at age 94 in 2003, and were interviewed by the founder of eHarmony to discover the secrets of a long and happy union.

In the early 1950s, Mrs. Langmuir became interested in the ideas and teachings of G.I. Gurdjieff, and became one of the founding members of the Gurdjieff Foundation of California in Los Angeles. She maintained her dedication to and leadership of the Gurdjieff Foundation throughout the remainder of her life. Also, in later years, she served on the board of the Panetics Society, dedicated to the amelioration of human suffering.

Music was always an important part of her life, and music often filled her home, shared with family and friends. She took a particular interest in young people; countless friends and relatives viewed her as surrogate mother and grandmother, a role she gracefully and willingly fulfilled. Diagnosed with terminal lung cancer in 2006, Mrs. Langmuir never worried or complained about her illness, but maintained an entirely positive attitude towards herself and others, remaining adventurously engaged in life to the very end.

Mrs. Langmuir first visited Martha’s Vineyard with her good friend and future sister in law, Edith Langmuir Leverenz, when they were teenagers. She and her husband David were long-time residents, spending summers with their children and grandchildren at the family home on East Chop.

A memorial service will take place on Saturday, August 8, at the Chilmark Community Church, 9 Menemsha Cross Road, Chilmark at 3 p.m.

Mrs. Langmuir is survived by her family: daughter Diana Rosenthal and her husband, Laurence Rosenthal; daughter Jean Langmuir; son Charles Langmuir; and five grandchildren, Celeste Allen, Jessica Blinn, Sophia Genone, Molly Langmuir and Jonathan Rosenthal.