In Siberian summers, MIT graduate student Seth Burgess tells me, the mosquitoes swarm thick enough to choke you. When he conducted fieldwork over several summers in the vast Russian wilderness, their buzzing filled his tent at night and their bodies littered his meals. After the arduous journey by car, bus, plane, and even helicopter to remote Siberia, he spent weeks floating down various rivers battling the insects and searching for rocks. Not just any rocks, though. Burgess is part of a large team answering questions about the greatest extinction event in earth’s history.

Around 250 million years ago, an enormous volcanic event occurred in present-day Siberia. Over a million-year span, lava flows (now called the Siberian Traps) covered an area as large as western Europe. Scientists have long believed there is a connection between the Traps and the Permian extinction of roughly the same time frame, when over 90 percent of life on earth vanished. Without a very precise timeline of the events, however, it has been difficult to identify whether the volcanic eruptions were the primary cause of extinction, or merely one among several. That’s where Seth Burgess’ work comes in.

At MIT’s Radiogenic Isotope Laboratory, Burgess has spent the last several years using some of the most meticulous and accurate techniques in the world to date rocks from the Siberian Traps. By narrowing down the eruption timeframe more accurately than previous estimates, he hopes to bolster the case for a causal relationship between the volcanic activity and the great extinction.

All the hard fieldwork in Siberia comes down to one thing: a quarry of zircon crystals, the mineral that holds the key to dating the Siberian Traps. When the crystals first formed in the volcanic eruptions, each possessed a set number of uranium atoms. Over millions of years, though, the uranium atoms decayed at a certain rate into lead atoms. By determining how many lead atoms now reside in each zircon crystal and how many uranium atoms remain, Burgess can tell with impressive precision how old each crystal is. Getting to that simple ratio, however, requires a 20-hour process of manual labor, complex chemistry, and delicate machinery. It’s a process that Burgess has had to repeat hundreds of times.

Straight out of Siberia, the zircon-containing rocks start out as softball-sized hunks. In a drafty storage facility near MIT’s campus, Burgess uses a series of machines designed to grind the rocks into progressively smaller pieces. A designated “rock crusher” (usually a first-year geology student) uses a sledgehammer to pound the rocks into golf balls. A jaw crusher machine then grinds them into dime-sized bits. Three more machines turn the rocks into a fine powder separated by particle size. Another machine isolates the magnetic components of the powder from the nonmagnetic ones, like zircon. Then Burgess must individually pick out the zircons—a faceted, yellowish crystal—under a microscope using a pair of tweezers.

Zircon crystals in hand, the chemistry is ready to begin. Meticulous protocol has made MIT’s lab one of the cleanest in the world, and minimal contamination means maximum accuracy. Burgess puts the crystals through a sequence of acid baths to dissolve the mineral, leaving each tiny sample a broth of acid and various atoms including uranium and lead. He then runs them through a chromatographer, the apparatus that separates the uranium and lead from everything else on a tiny filament.

Finally, the samples are ready to go into the mass spectrometer, a machine that separates atoms based on their weights. Sensors in the machine tally up the number of each atom, and Burgess monitors the readouts on a nearby computer. The ratio of uranium to lead atoms in each sample reveals when the rocks formed.

Though in the final stages of his research now, Burgess’ journey has not been an easy one. Other projects fell through before this one solidified, which is why he’s in his sixth—and hopefully last—year as a Ph.D. candidate. He’s at the lab by 6 a.m. every single day to run the various samples, interpret his data, and write a slew of research papers. The hours are long, the work is repetitive, and the lab can be lonely. Yet Burgess could not imagine himself doing anything else. Since he was a dinosaur-loving child in northern California, he always knew he wanted to study earth processes. After an undergraduate degree in soil science and a master’s degree in geology, he landed in the MIT lab of Sam Bowring, a renowned geologist with a fascination for any and all questions that can be asked of a rock. Burgess hopes his dedication will pay off in the coming months, when he submits the fruits of his labor to top science publications like Science and Nature.