Allan Hills A77304 meteorite, Allan Hills, Victoria Land, Eastern Antarctica, Antarcticai

Regional Level Types
Allan Hills A77304 meteorite	Meteorite Fall Location
Allan Hills	Group of Hills
Victoria Land	Region
Eastern Antarctica	Region
Antarctica	Continent

Ordinary chondrite, unequilibrated (LL3.7.10; S2; W2)
Find, 1977; 650.4 g

ALHA77304 is a small meteorite stone recovered in an early US-Japanese Antarctic search effort. The meteorite was largely covered by a thin brownish-black fusion crust. Thin sections revealed well-defined chondrules of various types (PO, POP, RP, BO), frequently rimmed with opaques, which are set in a matrix of comminuted silicate grains. A number of larger chondrules are elongated and somewhat intergrown with the matrix. Small amounts of troilite and Fe-Ni metal (kamacite; a Ni-rich phase) are present. Several minor silicates, oxides, and other minerals are reported in abstracts and elsewhere. Undulose extinction in fractured olivine grains indicate moderate shock level (S2). Some rust stains are present.

A 'plateau' involving 46% of the 39-Argon release data provides a 40-Ar—39-Argon age of ~4.5 Ga for some considerable portion of the ALHA77304 assemblage.

Alan Hills A77304 was the first LL3.7 meteorite to be recovered. 27 LL3.7 chondrites were listed as of August 2015.

What's in a name? Confusion sometimes occurs as one runs into other unofficial abbreviations such as (ALH77304) and (ALH 77304) even in the technical literature.

Other Regions, Features and Areas containing this locality

References