Overview
- An international team reported on June 18 that they identified microscopic grains of andradite garnet inside a 0.8 by 0.5 mm fragment of the Martian basaltic breccia NWA 8171 from the Royal Ontario Museum collection.
- Garnet is a mineral that records the temperature, pressure and chemistry of its formation, so even a few sub-millimeter grains can preserve direct evidence of the processes that affected ancient Martian rock.
- NWA 8171 is a breccia made of mixed rock fragments, which makes it a rich time capsule but also allows the possibility that the garnet-bearing clast was delivered to Mars before the meteorite formed.
- The research team will next measure isotope ratios in the garnet to test for known Martian chemical signatures, and a match would confirm in situ formation while a mismatch would point to an extra‑Martian origin.
- If the garnet is Martian, it could indicate impact-driven metamorphism, unusual magmas, or deep-crustal processes on early Mars and would open new avenues for studying the planet’s ancient interior.