Brownleeite
A manganese silicide found in a speck of comet dust collected high in Earth's atmosphere.
Key facts
- Formula
- MnSi
- Family
- Phosphides, carbides, nitrides and silicides
- Crystal system
- Cubic
- First described
- an interplanetary dust particle, 2008
Brownleeite was described in 2008 from an interplanetary dust particle collected in Earth's stratosphere by a high-flying aircraft, probably dust from a comet. It is named after Donald Brownlee, the American astronomer who pioneered the collection of cosmic dust and led NASA's Stardust mission.
What it is
Brownleeite is a manganese silicide, a compound of manganese with silicon. It forms only where oxygen is extremely scarce, perhaps by condensation from hot gas in the early Solar System.
Where it is found
It was found as tiny grains in an interplanetary dust particle, a fragile grain of space dust caught on collectors flown in the stratosphere. The particle may come from comet 26P/Grigg–Skjellerup, whose dust Earth crosses each year.
How it is recognised
It is identified by transmission electron microscopy, because the grains are only nanometres to a few hundred nanometres across.
Did you know?
Brownleeite was the first new mineral found in a comet dust particle.
Brownlee's Stardust mission brought back dust from comet Wild 2 in 2006.