[meteorite-list] Santa Rosa - Part 2 of 2

From: Bernd Pauli HD <bernd.pauli_at_meteoritecentral.com>
Date: Thu Apr 22 09:41:10 2004
Message-ID: <3A8AE33F.4F2562BF_at_lehrer1.rz.uni-karlsruhe.de>

BUCHWALD V.F. (1975) Hansbook of Iron Meteorites, Vol. 3,
pp. 1075-1080, excerpts: Santa Rosa, Boyacá, Colombia

Description

The 612 kg main mass, which for some years served as an anvil in Santa
Rosa, measured 77 x 49 x 45 cm (Ward 1907). It is covered with
regmaglypts, 3-7 cm across and 1-2 cm deep, over a large part of its
surface; and the fusion crust of magnetite plus wüstite is preserved in
numerous places, albeit in a somewhat corroded state. The well developed
regmaglypts on the individual specimens prove that the meteorite burst
high in the atmosphere.
Etched sections are anomalous in displaying no clearly identifiable
Widmanstätten structure. At high temperature the metal was evidently a
polycrystalline aggregate of austenite (taenite) grains, each 2-5 cm
across and slightly elongated. The presence of parallel - somewhat
flattened - cylinders of troilite is very characteristic. The individual
troilite bodies seem to be shaped as belemnites or small cigars,
typically 4-10 mm thick and 4-6 cm long and tapering to a point at both
ends.
Santa Rosa is an intriguing meteorite, which does not easily surrender
to interpretation. Also, chemically, it is rather unique, having only
Chihuahua City as its near relative. Farther away stand Bendego and
Saint Francois County.
With respect to the many pseudometeorites and artificially reheated
specimens often labeled Rasgata, I refer to the description and figures
in Buchwald & Wasson (1968).


Best wishes,

Bernd
Received on Wed 14 Feb 2001 02:57:51 PM PST