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Met Name

Met Type

Thin Sections

78.1 and 38.2 grams.   Iron, IIIAB

TKW 6.66 kg. Fall not observed. Found 1969, Zacatecas, Mexico. The coordinates for the map below (22° 48' N, 102° 33' W) were found in Buchwald.



   

Steve writes:

A local resident near the city of Zacatecas, Mexico, found a 6.66 kg (14.5 pound) meteorite that was subsequently purchased by Richard Dalsin of Minneapolis, Minnesota, in February, 1969. V. F. Buchwald examined the specimen and determined that it was distinct from the 1792 meteorite bearing the same name. Consequently it was given the official designation of "Zacatecas (1969)". The complete specimen was then given to the Smithsonian Institution’s National Museum of Natural History in Washington, D. C.

Later, another mass was found in the same area that proved to be chemically identical to the first mass. It had been used for 40 years as an anvil and shows signs of alteration as a consequence of continued pounding (the Widmanstätten pattern on pieces cut from one corner shows progressively less definition toward the outer edge). This second mass is now the source for all of the publicly available Zacatecas (1969) samples.

Zacatecas (1969) is a medium octahedrite type IIIAB nickel-iron meteorite that largely re-crystallized due to intense heating as a consequence of having passed very close to the sun. For that reason, there are no clear Widmanstätten lines present in the majority of Zacatecas material, though remnant crystalline patterns can be seen at the edge of full slices cut from this meteorite.

The two pieces shown in Photos 1 and 2 were acquired indirectly from an old estate collection. They were originally etched very deeply, presumably because the original preparer did not realize they were recrystallized and therefore left them in the acid too long in an attempt to bring out the non-existent Widmanstätten pattern. After acquiring them they were sanded, polished, and then re-etched to reduce the distance between the harder troilite inclusions and the softer nickel-iron that had receded more during the prior etching. The larger piece has an interesting inclusion on its front side (Photo 3); on the opposite side is a small carbon nodule behind that inclusion about which the meteorite’s 60 degree re-crystallization pattern is quite obvious (Photo 4).