A meteorite formed in Mars provided the chemical proof of magma in the Martian mantle. Tissint meteorite that fell to Earth in 2011 have crystals of olivine. This could only have formed in changing temperatures as it was rapidly swirled about in magma convection currents. The crystals were formed 574 to 582 million years ago.
Olivine, a magnesium iron silicate crystallises from cooling magma. This is common in earth’s mantle. On Earth’s surface, it’s found in igneous rock. This is common in meteorites and in Mars. The the presence of olivine on the surface of Mars has previously been taken as evidence of the planet’s dryness
When the olivine crystals in the Tissint meteorite was closely studied it had irregularly spaced phosphorus-rich bands. This is a process called solute trapping and it is common on earth. This occurs when the rate of crystal growth exceeds the rate at which phosphorus can diffuse through the melt. Then phosphorus enters the crystal. The olivine crystals also revealed traces of nickel and cobalt. This shows that the meteorite originated in Martian crust, a depth of 40 to 80 kilometres.
The team also found that the mantle probably had a temperature of around 1,560 degrees Celsius. This is very close to the temperature of Earth of 1,650 degrees Celsius during the Archean Eon, 4 to 2.5 billion years ago.
The research has been published in Meteoritics & Planetary Science.