Lunar B for sale


LUN B - Mare Basalts

Synonyms: lunar mare basalts, lunar mare gabbros


General: As opposed to the lunar anorthositic highland breccias, the members of the LUN B group are from the smooth lowlands of the Moon, the so-called Maria of the near side. They represent igneous rocks of basaltic to gabbroic compositions, and are much younger than their anorthositic cousins - but at least as interesting, and exceedingly rare.


Description: Most members of this group are dark igneous rocks, exhibiting fine-grained basaltic to coarse-grained gabbroic textures, similar to terrestrial volcanites and plutonites, such as basalts, dolerites, and gabbros. On most individuals recovered so far a fusion crust is absent due to an extended terrestrial residence time, and severe weathering. The only light-colored mare basalt from Antarctica, LAP 002205 and its respective pairings, show a dull black fusion crust.


Mineralogy: Consisting of phenocrysts of olivine and augite set within a fine- to coarse-grained matrix of plagioclase and pyroxene, the lunar mare basalts are typical igneous rocks. As accessory minerals they contain chromite, ilmenite, apatite, troilite, and minor nickel-iron metal. Two subgroups exist: the classical, more fine-grained mare basalts, and the more coarse-grained mare gabbros.


Formation history: Lunar mare basalts are much younger than the anorthositic highland rocks. They were formed during volcanic eruptions within large basins, mostly located on the near side of the Moon, their shapes delineating the renowned face of the "Man in the Moon". Mare gabbros display much coarser grain sizes and a cumulate intergrowth. This suggests formation from similar magmas that were trapped in magma chambers or deeper layers of the lunar surface. These magmas experienced lower cooling rates, resulting in a prolonged crystal growth and the formation of cumulate, gabbroic textures.


Origin: Planetary. Comparisons to the lunar samples that have been returned by the Apollo and Luna missions have shown that the meteorites of this group are genuine samples of the Earth's satellite, the Moon. Have a look at our introductory section about the LUN group for further details. All lunar mare basalts, and gabbros are thought to have originated from the lunar Maria on the near side of the Moon, with the exception of NWA 773 that is thought to have been ejected from the Aitken basin on the far side of the Moon - a large impact structure near the lunar South Pole.


Members: Only three of the six LUN B members are available to private collections, two representing classical mare basalts, and only one representing a gabbro. The mare basalts are Dhofar 287 from Oman, the unbrecciated NWA 032, and its respective pairing NWA 479 from Khter n'Ait Khebbach, Morocco. Two mare gabbros from Antarctica, Yamato 793169 and Asuka 881757, are locked away with international research institutions, while NWA 773 and pairing group remains the only lunar mare gabbro available on the private market. It is an olivine gabbro with adhering regolith, and some researchers also group it with the mingled breccias, although it shows strong affinities to the LUN B group, and the mare gabbros.

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