Melliniite
A nickel-rich phosphide with four metal atoms per phosphorus, first found in a primitive achondrite.
Key facts
- Formula
- (Ni,Fe)4P
- Family
- Phosphides, carbides, nitrides and silicides
- Crystal system
- Cubic
- First described
- the acapulcoite Northwest Africa 1054, 2005
Melliniite was approved as a new mineral in 2005 from Northwest Africa 1054, an acapulcoite found in the Sahara, and described in 2006. It is named after Marcello Mellini, an Italian professor of mineralogy who advanced meteorite research in Italy.
What it is
Melliniite is a phosphide richer in metal than schreibersite: it has four atoms of nickel and iron for each atom of phosphorus. Its structure is cubic, unlike that of the tetragonal schreibersite.
Where it is found
It was found as tiny grains in the metal of NWA 1054, an acapulcoite. Acapulcoites are primitive achondrites, rocks from an asteroid that was heated until it began to melt but never fully separated.
How it is recognised
It is identified by microprobe analysis and X-ray diffraction of grains only tens of micrometres across.
Did you know?
Acapulcoites are named after the Acapulco meteorite, which fell in Mexico in 1976.
Northwest Africa meteorites are numbered in the order they are classified; more than 15,000 have now been named.