On Thanksgiving Day 2002, my family broke into a quarry near Lee Vining, Calif., and carried away several pounds of rocks in three paper bags. It wasn’t much of a burglary, as burglaries go — we parked our minivan on a deserted road in a lodgepole forest and climbed over the steel gate without any employees bothering us. They were all home in June Lake, the last hamlet before Mammoth, to the south, or in Mono City, a string of thirty mobile homes on Lundy Creek. We were staying in Mono City too, in the thin-walled double-wide of a friend who wasn’t around, and we spent a great deal of time outside.

The air was absolutely still. The sweet, dusty scent of sagebrush and the tang of the lodgepoles filled our nostrils, flared wide in the chill. At our backs the Sierra sprang up like a fortress; below was the Mono Basin, with the salt lake full of sky. It was midday, and the mounds of rock were white as bone.

The pumice from the quarry was used in industrial abrasives. The jagged hunks of obsidian lying here and there made surgical scalpels. The obsidian and the pumice were formed from the same rock, frozen solid or perforated with air, jet black or grayish white, and they were new, just 600 years old. My father picked up a piece of pumice the size of a cat’s head, and at his feet the heap of porous white lumps rustled as they fell to fill the gap. He said, “We’ll never have another callus, girls.”

This wasn’t funny until we remembered that people rubbed their feet with bits of pumice to get off the dead skin. Then it was hilarious. There was enough pumice on that hillside to keep the whole state in soft tootsies, even the people in L.A., we imagined. We’d never been farther south than Fresno, though we’d lived in California all our lives.

Home was a very specific portion of the state, running from the Placerville Kmart on Highway 50 to the crest of the Sierra, then through the canyons to Monitor Pass and in a narrow strip along Highway 395, all the way down to Mono. When the night wind howled outside our borrowed double-wide, I felt as if I were sitting in an open cardboard box under the sky. I picked through the bags of rocks by the door, sorting them and running my fingers over their surfaces. Pumice is rough as coral, brittle and light. Obsidian is as whorled with fracture lines as hunks of shattered sheet glass, and it slices your hands. Sometimes we found arrowheads of obsidian in the rivers or in the hills above Mono, and when I was older, coring trees for the Forest Service in Nevada, I woke one morning after pitching my tent in the dark to find a flow of arrowheads for yards around me, glinting as the sun came up.

The desert was a place where my family melded together because we had no one else. We walked up Lundy Canyon and slid rocks across the frozen lake, and we scrambled up to the top of Obsidian Dome. We walked through pine forests where the trees were 25 feet apart for lack of water and the fallen needles matted together like hair over the soil. My mother peed in plain sight of the road, and we were amused instead of mortified.

And yet, though we were closer together, in a place so large some of the space had to go between us.

On Thanksgiving evening, we sat in the flimsy house with a turkey on the card table in front of us and the wind muttering outside. It was my first Thanksgiving as a vegetarian, but I had promised that I would eat some meat with my family because it was, after all, Thanksgiving. We went around the table and said our “thankful-fors”: someone blessed the rocks in paper bags, someone the paper-bag house. My dad passed around the rolls. But when the time came for me to eat, the bird had become a cadaver. The grooves of its bones were lined with red tendons; its filmy skin bore the imprint of vessels. I turned away. Under the table I could feel the grit from the sacks of rock, embedded in the carpet and abrading my soles. My parents had breast meat, and my sisters, drumsticks. I looked out the window at the empty desert.

The paper bags of pumice and obsidian came back with us over the crest and sat for two years against the wall of the garage, leaking sand and fragments of black glass. Bits of sagebrush picked from hiking boots, several pairs of ski poles and piles of sea glass gathered to keep them company. They probably would have stayed there indefinitely, except that in February of 2004, my father got a job in Switzerland, and by May, everything from our house in California was in a temperature-controlled storage facility and my family was 5,000 miles away, experiencing the deluge of paperwork that constitutes moving to la Suisse. I don’t think the bags of rocks made it into the storage unit. I’m pretty sure we dumped them in the woods.

When I came to school that August, I brought with me four boxes of clothes and several hundred books. I had lived out of a suitcase at a friend’s that summer, returning to the house once a week to brush away the cobwebs; all mementos except the books were stored. But in October, a package came from the friend in Mono City. I opened it on the post office stairs with the edge of a key. Inside were four pinecones — Jeffrey, sugar pine, white pine, red pine — and a Ziploc bag of sagebrush tucked in a corner. At the very bottom, shaken there during its cross-continental passage, was a hunk of obsidian.

It fit neatly in my hand, with a divot for the ball of the thumb and a ridge along the base of the fingers. A series of tiny fracture lines ran like streams across its surface, and the edges were fine and sharp. The center was blacker than any coal. I turned it over and over in my hands, running my thumb along the thin edge until it cut, deep and clean, into the flesh. There was no pain. I sat down on the post office steps and set the box beside me. Then I cried until I couldn’t see the shining thing in my hands.