A Rock From Mars Is at Least 4.1 Billion Years Old. What Does It Tell Us?

A Sahara meteorite called Teghaza 001 is a piece of ancient Mars crust. A new Science paper dates it and finds signs of early water. Here is what holds up and what does not.

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한국어 요약
2022년 사하라(말리)에서 발견된 약 800g의 화성 운석 Teghaza 001이 최소 41억 년 전에 형성된 초기 화성 지각의 조각이라는 논문이 2026년 10월 29일 Science에 실렸습니다. 지르콘 우라늄-납 연대가 약 41.14억 년이고 다른 측정법도 같은 값을 가리키지만, 이 값은 암석이 생긴 때가 아니라 물에 의한 변질이 일어난 때일 수 있어 '최소 41억 년'이라고 표현합니다. 이 암석에는 물과 반응한 광물이 있고, 별도 논문은 당시 화성 물의 중수소 비율이 지구 바닷물의 약 2배 이상이라며 화성이 수소를 일찍 우주로 잃었다는 모형을 뒷받침한다고 밝혔습니다. 기존에 알려진 고대 화성 운석은 ALH 84001과 Black Beauty 두 종뿐이었다는 점에서 의미가 큽니다. 다만 이 돌이 화성 어디서 왔는지는 알 수 없고 NASA가 후보 13곳을 제시했을 뿐이며, 한 개의 돌로 초기 화성 전체를 설명할 수는 없습니다.

Most rocks from Mars that fall to Earth are young. A new study says one found in the Sahara is not. The meteorite, called Teghaza 001, formed at least 4.1 billion years ago. That makes it a rare sample of the planet’s earliest crust.

What was found

Teghaza 001 was found in the Sahara, in Mali, in 2022. According to the Science paper, it is eight stones with a total mass of 798.5 grams. The largest is 442 grams. Researchers at the University of New Mexico first confirmed it was from Mars by matching its oxygen isotopes, which act like a chemical fingerprint, to other Martian rocks, NASA says.

The paper was published online on October 29, 2026. Its lead author is Yang Liu of NASA’s Jet Propulsion Laboratory. NASA funded the work.

How old is it?

The team used several clocks, and they agree:

Zircon is useful because it traps uranium when it forms, and uranium turns into lead at a steady rate. It works like a built-in stopwatch.

There is one catch, and the authors state it themselves. The paper says the date of about 4.1 billion years may mark a later event, when hot water changed the rock, rather than the moment the rock first formed. Their reading is that the rock formed no later than that date. This is why careful writers say “at least 4.1 billion years” and not “exactly 4.1 billion.”

What kind of rock is it?

Teghaza 001 is a slowly cooled igneous rock, which means it hardened from molten rock underground. The paper calls it a leuco-gabbro, a rock rich in a pale mineral called plagioclase. A companion paper calls it a gabbroic diorite. NASA first thought it was a shergottite, the most common kind of Mars meteorite, but that was an early guess.

The paper says its chemistry points to a mantle source with a “primordial” makeup that is different from the sources of other Mars meteorites. The authors read this as a sign that Mars’s deep interior was uneven very early. That is their interpretation, not a settled fact.

Why it matters

NASA counts about 435 known Mars meteorites. The Science paper says only two ancient ones were known before: ALH 84001, which is almost one mineral, and NWA 7034, nicknamed Black Beauty, a mix of broken fragments. NASA counts Teghaza 001 as one of the three oldest.

The counts differ a little in wording. NASA gives about 2.1 billion years for Black Beauty as a rock, while the paper notes that some fragments inside it are older than 4.3 billion years. The point is the same: Teghaza 001 is a whole, intact piece of old crust, and that is rare. Think of it as a page from the first chapter of a book where nearly every other page we have is from the end.

Clues about water

The rock holds minerals that changed after contact with water-rich fluids. A separate Science Advances paper from June measured hydrogen in its minerals. It found a heavy-hydrogen share at least about twice that of Earth’s seawater. The authors say this supports models in which Mars lost light hydrogen to space quickly.

NASA says the results point to a more active early water cycle. One of the study’s authors said the rock may also hold an imprint of Mars’s atmosphere as it lost water, and the word “may” matters there. A reviewer called the rock a “Rosetta Stone for Mars”, according to NASA.

What we do not know

  • Where it came from. NASA says no one will know exactly. The team compared the rock’s chemistry with orbiter measurements and found 13 places on Mars that match. A match does not prove it came from there.
  • The full story of its trip. The paper says a strong impact, at about 20 gigapascals of pressure, threw it off Mars. The paper does not give an exact date for that launch.
  • How typical it is. One rock cannot describe a whole planet. It adds a data point, and other early rocks may look different.
  • Life. The papers are about rocks, water, and heat. They do not claim any sign of life.

JPL’s Yang Liu told NASA the team has only scratched the surface. Other labs can now test the same material.

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