Classification led by Jen Mitchell
This meteorite belongs to Sean Mahoney and is comprised of multiple individual stones found near Oum El Assel in Algeria.
This meteorite will possibly receive an official name of 'Tindouf ***' - to be confirmed by the Nomenclature Committee of the Meteoritical Society.
The type specimen (20.75 g) will be on deposit at the University of Plymouth, along with a single, polished thin section.
This meteorite was found buried in the ground during a hunt for more material belonging to OSM 011a. Analysis by the Space Rocks UK team revealed that this buried material is most likely an entirely different meteorite to the one found on the surface!
BSE image of OSM 011b, with visible clasts outlined.
A Little bit of Everything
Much like OSM 011a, this meteorite is a breccia - a rock composed of different rock types that have been stuck together. At present, we've been able to identify at least 6 different types of eucrite in a single piece! This meteorite very, very heavily recrystallised which makes our job a little harder.
Breccias can be divided into a number of categories depending on the diversity of the rock types that they're made from. OSM 011b is considered a polymict eucrite breccia, meaning that it is composed of various types of eucrite material which we can identify by mineral composition and texture. On asteroids, breccias are formed by impact events breaking up the crust and mixing material together before it is lithified into a solid piece.
Similar, but Not the Same
This graph is how pyroxene compositions are plotted - showing the endmember series from enstatite (Ens, magnesium endmember), ferrosilite (Fs, iron endmember), and upwards towards wollastonite (Wo, calcium endmember).
Although they were found on top of each other, OSM 011a and OSM 011b have different pyroxene compositional trends, suggesting that they actually represent distinct eucrites. Even if there is a little overlap (to be expected when dealing with breccias), most of the points form separate clusters. These compositions reflect different magmas and crystallisation histories.
Pyroxene composition plot of OSM 011a and OSM 011b.
Sean is a meteorite collector and dealer based in Spain, and a registered member of both the IMCA and GMA.
You can find out more about Sean's meteorite collection, OuterSpacer Meteorites, on his web page.
Meteorite Girl UK