[meteorite-list] Troilite again !

From: bernd.pauli_at_paulinet.de <bernd.pauli_at_meteoritecentral.com>
Date: Fri Jul 22 17:56:50 2005
Message-ID: <DIIE.0000003200003B06_at_paulinet.de>

NORTON O.R. (2002) The Cambridge Encyclopedia of Meteorites, Glossary, p. 313:

Sulfide; hexagonal - a bronze-colored iron sulfide occurring as an accessory
mineral in nearly all meteorites. It is found as nodules in iron meteorites and
is often associated with graphite nodules. In chondritic meteorites it is usually
found as small blebs or grains in both chondrules and matrix averaging about 6 wt%.
It differs from pyrrhotite by lacking an iron deficiency and is not magnetic.

McSWEEN H.Y. (1999) Meteorites and Their Parent Planets (Cambridge
University Press, Glossary, p. 288) - Appendix of minerals, p. 285:

a) Brass-colored sulfide, FeS, hexagonal, a common constituent of most
   classes of meteorites.

b) p. 57: Most chondrites are speckled with small bits of highly reflective
   metal and brassy sulfide ... The sulfides are mostly a combination of
   sulphur with iron (the mineral troilite), although enstatite chondrites
   contain a bewildering variety of sulfides, including combinations with
   calcium (oldhamite - CaS), manganese [alabandite - (Mn,Fe,Mg)S],
   magnesium [niningerite - (Mg,Fe)S], zinc [sphalerite - (Zn,Fe)S], and
   iron and chromium (daubreelite - FeCr2S4).

c) p. 194: Troilite (iron sulfide) is almost ubiquitous, forming dark, rounded
   nodules [in iron meteorites]. Inclusions of this phase were first observed
   by the Jesuit priest Domenico Troili in 1766, but a century elapsed before
   accurate chemical analyses proved that it wasdistincr from pyrite (iron
   disulfide), the fool's gold commonly found in terrestrial rocks. Sulphur is
   highly soluble in molten iron but practically insoluble in solid iron, so it
   is necessary for this element to form a sulfide as the metal crystallizes.


   Best wishes,

   Bernd
Received on Fri 22 Jul 2005 05:56:48 PM PDT