L/LL6 (or L)
Found 1975
28° 41′ S., 141° 59′ E. A mass of 27 kg was found by a rabbit trapper 5 miles west of Corkwood Tank in Queensland, Australia. Naryilco was analyzed and classified at the Institut für Planetologie, University of Münster, Germany. The meteoriteWork in progress. A solid natural object reaching a planet’s surface from interplanetary space. Solid portion of a meteoroid that survives its fall to Earth, or some other body. Meteorites are classified as stony meteorites, iron meteorites, and stony-iron meteorites. These groups are further divided according to their mineralogy and is a brecciaWork in Progress ... A rock that is a mechanical mixture of different minerals and/or rock fragments (clasts). A breccia may also be distinguished by the origin of its clasts: (monomict breccia: monogenetic or monolithologic, and polymict breccia: polygenetic or polylithologic). The proportions of these fragments within the unbrecciated material composed of angular, cm-sized light and dark lithic clasts with shock veins, the result of prolonged impacts on its parent bodyThe body from which a meteorite or meteoroid was derived prior to its ejection. Some parent bodies were destroyed early in the formation of our Solar System, while others like the asteroid 4-Vesta and Mars are still observable today.. Subsequent impacts generated enough heat to cause minor melting along grain boundaries, fusing the different clasts together.
ORDINARY CHONDRITEWork in Progress Ordinary chondrites (OCs) are the largest meteorite clan, comprising approximately 87% of the global collection and 78% of all falls (Meteoritical Society database 2018). Meteorites & the Early Solar System: page 581 section 6.1 OC of type 5 or 6 with an apparent shock stage of S1, COMPOSITIONS | ||
---|---|---|
Fa | Fs | |
H | 16–20.4 | 14.5–18.1 |
H/L | 19.5–21.8 | 17.2–21.2 |
L | 22–26 | 18.7–22 |
L/LL | 25.5–26.5 | — |
LL | 26–33 | 22–26 |
It was demonstrated by Szurgot (2016) that the mean atomic weightMass of a neutral atom of a nuclide - also called "atomic weight." The atomic weight of an element is the weighted average of each isotope. (Amean) of meteorites can be used to resolve the OC groups, including the intermediate groups L/LL and H/L. Amean values can also be predicted through various equations based on other parameters such as atomic Fe/Si ratio, grain densityMass of an object divided by its volume. Density is a characteristic property of a substance (rock vs. ice, e.g.). Some substances (like gases) are easily compressible and have different densities depending on how much pressure is exerted upon them. The Sun is composed of compressible gases and is much, and magnetic susceptibility, and these Amean values all consistently resolve these groups into the ordered sequence LL < L/LL < L < H/L < H. Furthermore, it was demonstrated that Amean values are lower for unequilibrated type 3 samples than for equilibrated samples within each OC group due to the presence of water; Amean values for petrologic types 4–6 are indistinguishable within each group.
Diagram credit: M. Szurgot, 47th LPSC, #2180 (2016)
Amean based on chemical composition (Eq. 1), Fe/Si atomic ratio (Eq. 2), and grain density (Eq. 3) Examples of other L/LL6 group members include the Acfer meteorites 041, 149, and 315, the HaH meteorites 046 and 074, Holbrook, and Sahara 97012. The Naryilco specimen shown above is a 1.44 g partial slice. A superb large slab can be seen on display at the Smithsonian Institution, Washington D.C.