Petra began collecting stones in earnest when she and Nenni moved into Sunnuhlíð in 1946. The reason was simple: for the first time, she finally had a home of her own in which to keep them. She had been observing these stones in the mountains since childhood, so in fact, she had been logging them in her mind. Only when she had a house of her own did she start taking them home with her to keep. Or, as she put it herself: “I knew where to go when I really started collecting.”

Many of the stones Petra discovered as a child are no longer part of her collection. Both foreign and Icelandic collectors had removed them before she had the means to collect them herself. Petra also left countless stones where they had rested for millions of years. Most of these stones were too large to carry, but she visited them regularly and studied them closely. She “went to greet them,” as she herself described it, and she was never tempted to break them apart to bring a piece home. In this sense, her stone collection existed in two separate places: at Sunnuhlíð and within her own mind. The latter extended throughout the fjord and far beyond.

For the first twenty years of her collecting, Petra gathered stones from the shoreline and the mountain range north of the fjord. She would step out the front door of Sunnuhlíð and follow her path up the slopes and into the mountains above. Until the mid-1960s, there were no roads leading south of the fjord or into the neighboring fjords south of Stöðvarfjörður. A road around the Kambanes peninsula was not completed until 1962, and a bridge over the Stöðvará River was built that same year. A drivable road north to Fáskrúðsfjörður did not open until 1953. Stöðvarfjörður was isolated well into the age of automobiles, delaying Petra’s exploration of nearby regions. As a result, the vast majority of her stones come from Stöðvarfjörður and East Iceland, as she rarely searched for stones in other parts of the country.

Many people assume that a stone collector must be a little eccentric, and over the years, Petra heard that opinion often. She was reminded that it would be more fitting for her to stay at home baking or attending to other domestic tasks better suited to a housewife. Petra let such remarks fall on deaf ears and instead followed her urge to collect. She did, however, agree that she must have been somewhat unconventional to take pleasure in gathering stones - but it was a need she could not resist.

Petra possessed a special gift for finding beautiful stones. Many people accompanied her on stone-hunting excursions and later described how she would pick striking stones from their path - stones they themselves had walked past without noticing. Some of these she retrieved from muddy ground where no indicators of anything of interest were to be found.

Petra often compared stone collecting to fishing. What justified the effort of carrying the stones home was the thrill of the search and the satisfaction of the “catch.” No two stones were ever the same, and she always discovered something new in each one she found. This creative force of nature called to her, and she could never ignore that call. Petra said that the joy of finding a stone was always tinged with a trace of guilt. She often felt as though she were taking something from the hidden folk. Although she had never seen them herself, she never doubted their existence and believed she was forgiven. As proof, she pointed to the fact that she had never fallen badly or injured herself in all the years she ventured into their realm. She interpreted this as a sign that her stone collecting existed in peace and harmony with those she believed to be the rightful owners of the stones.