[meteorite-list] History of etching process for revealing Widmanstatten structure

From: Bernd Pauli HD <bernd.pauli_at_meteoritecentral.com>
Date: Thu Apr 22 09:44:15 2004
Message-ID: <3B3E2ED3.5E8242A2_at_lehrer1.rz.uni-karlsruhe.de>

Mike Mitchell wrote:

> My grandfather, Oscar Reberholt, worked on meteorites at the Smithsonian
> Museum of Natural History in Washington, DC, sometime between 1930ish
> and 1950ish ... Family history has it that he worked on a way of "polishing"
> meteorites. And there is some contention that he actually invented the
> method.


Hello Mike and List,

BURKE J.G. (1986) Cosmic Debris, Meteorites in
History (University of California Press, pp. 122-128):

Carl von Schreibers, director of the Vienna mineral and zoology cabinet,
named the structure after Aloys von Widmanstätten, who, he wrote,
observed it in 1808 on a polished and etched surface of the Hraschina
meteorite. In fact, William Thomson, who was involved in the Siena fall
controversy, published a description of it in 1804. He polished a
section of the Krasnojarsk pallasite and treated it with weak nitric
acid to prevent rusting. Thomson observed that there were three kinds of
iron: the broad lamellae that intersected mutually at angles of 76° and
104°; thin strips adjacent to these; and material in the rhombic or
triangular areas enclosed by the lamellae and strips (fig. 22, no. 5).
He also found that the three kinds of iron dissolved in nitric acid at
different rates: first, the broad lamellae [kamacite]; next, the iron
enclosed in the geometric spaces [plessite]; and finally the thin
brilliant strips [taenite].


Best wishes,

Bernd
Received on Sat 30 Jun 2001 03:56:03 PM PDT