Francis Lopez spent the last 60 years as a cartographer with the U.S. Geological Survey. He traveled to Brazil to update its mapping technology in the 1950s and 1960s, and he later worked in the Middle East.

But nowhere in his Potomac home was there a prized map or an ancient atlas from his years on the job or his extensive overseas trips. Possessions meant little to him.

"He could look at an old map and study it for hours, and that was sufficient for him to own it forever," said Crawford Lopez, his son.

After retiring in the mid-1980s, he continued to spend long hours at the Geological Survey as a volunteer. He did cataloguing work, which helped him cope with the slow death of his wife from Parkinson's disease in 1999.

"Lopey," as he was known, helped determine what was saved and what was disposed of -- an ideal task for a technician so focused on practicality, said Maurice J. "Rick" Terman, a geologist and scientist emeritus at the Geological Survey.

If it didn't belong, out it went.

"Guys like myself are pack rats; we'll save anything," Terman said. "He was insistent it had to have a purpose. . . . Lopey never had that sense of ownership, even if he produced the object."

Francis Xavier Lopez, 80, died Oct. 16 of a cerebral hemorrhage.

His attitude toward belongings was well known in his family. Crawford Lopez said his father used to tease him about his antique car collection. He once framed a small photograph of his son's 1920 Rolls-Royce and told friends that the automobile was his "grandchild." (That stopped when he got actual grandchildren.)

For Francis Lopez, there was an element of unease to collecting. He had few comforts growing up, and in fact was lucky to grow up at all. In a family with 13 children, he was one of only four to live past the teen years.

The family members fled the Mexican revolution and immigrated in the 1920s to Chicago, where they became mired in poverty on the South Side.

At 13, Lopez was thrust into adulthood after his father's fatal heart attack. He went to work shining shoes and delivering newspapers around Chicago.

He got smart fast. On his downtown paper route, he brought along an irresistibly cute younger brother. Who wouldn't buy a paper from him with a cherubic tot in tow?

Despite those desperate Depression days, he stayed in school and showed an independence of thought and precociousness that sometimes invited trouble. A nun in Sunday school rapped his knuckles with a ruler for questioning the Bible story of Jonah and the whale. On a visit to the Field Museum, he had learned that whales' throats are too small to swallow humans. The nun's violent reaction left him unimpressed with religion, and he soon left the church.

He had taken drafting classes in high school and junior college. With that expertise, he was hired by the Geological Survey during the wartime crunch for workers in the early 1940s. He put in long and laborious days in Washington, churning out defense-related charts to help the war effort. Working nearby was a map editor, Anna Crenshaw.

There appeared to be much to keep them apart. She was the Bryn Mawr-educated daughter of a Presbyterian missionary and had grown up in China. And she was nine years older.

"My father was absolutely fascinated by my mother," said Crawford Lopez, a consultant in water pollution control. "She was the first woman he knew not the least bit interested in being a mother and housewife."

He proposed to her when he was 21 and she was 30. She said she would not marry "a child" and told him she wanted to wait a year. They waited, then wed.

The union was not without its problems. His mother-in-law never entirely approved of the match, often referring to Lopez as "that Spaniard."

"Mexican, Mother, Mexican," Anna Crenshaw Lopez replied forcefully each time.

Francis Lopez, though proud of his heritage, never let his background become an issue in the family or at work. At the Geological Survey, his self-effacing personality helped smooth relations between U.S. officials and Brazilians during his South American stay.

He could be charming and outgoing, whereas his wife was shy and preferred a small circle of intimate friends. Lopez had a greater need for company, which he fulfilled by starting conversations with strangers at the grocery store or on the street.

"He really valued people for what they could share with each other," said his daughter, Luisa Lopez, a social work administrator. "He got very frustrated when people couldn't see the strength and the value of that."

In the late 1940s, Lopez and his wife bought a few secluded acres in Potomac, where they designed a split-level contemporary home inspired by Frank Lloyd Wright's drawings. She dug the foundations, but he did most of the building work.

He spent considerable time in the sunny living room poring over three daily newspapers: The Washington Post, the New York Times and the Christian Science Monitor, which he liked for its thoroughness. He also enjoyed tinkering with the home -- its floors or its leaky goldfish pond -- anything to be useful.

As for his effects, forget antique furniture. He preferred something more modern and cushiony. "If you couldn't sit in a chair, it wasn't worth owning," he would say.

Clockwise from above: Lopez about 1944; Lopez and his wife, Anna, right, and sister-in-law Martha Crenshaw, left, about 1944; Lopez in the 1960s; the Lopezes in later years.