"Green Glass Sea" is about Trinity, where the first bomb was dropped, and trinitite, the faintly radioactive fused green glass from the Trinity site that can be had in small or large pieces on eBay, even to this day.
The story is a memoir of the life of the small daughter of an atomic scientist, who recounts the events leading up to and following Trinity in heartbreaking Klages style:, simple, subtle, emotionally powerful writing that will knock you on your ass again and again as you read it.
Now "Green Glass Sea" is on Strange Horizons, the excellent online sf magazine, and free for all to read. If you haven't read Klages before, you're in for a treat.
In the summer of 1945, Dr. Gordon was gone for the first two weeks in July. Dewey Kerrigan noticed that a lot of the usual faces were missing from the dining hall at the Los Alamos lodge, and everyone seemed tense, even more tense than usual.Link
Dewey and her father had come to the Hill two years before, when she was eight. When he was sent to Washington, she came to live with the Gordons. They were both scientists, like Papa, and their daughter Suze was about the same age as Dewey. Dewey's mom hadn't been around since she was a baby.
One Sunday night Mrs. Gordon had shooed the girls to bed early, then woke them before dawn for a hike with some of the other wives, many of whom also had jobs and titles other than Mrs. They carried blankets and sandwiches and thermoses of coffee out to a place on the edge of the mesa where they had a clear view of the southern horizon and sat in the still early darkness, smoking and waiting.