I agree. I actually missed the dial being meteorite. Here is one of my bronze, but it doesn't have the prestigious piece of space rock dial. IMO I'd rather have the Muonionalusta over Gibeon, but I have one meteorite watch and that's all I need.
The Muonionalusta, probably the oldest known meteorite (4.5653 billion years), marks the first occurrence of stishovite in an iron meteorite. Stishovite, a high pressure polymorph of SiO2, is an exceptionally rare mineral...and has only been found in association with a few meteorite impact structures.... Clearly, the meteoritic stishovite cannot have formed by isostatic pressure prevailing in the core of the parent asteroid.... One can safely assume then that stishovite formation (in the Muonionalusta meteorite) is connected with an impact event. The glass component might have formed directly as a shock melt....or by post-shock processes (e.g., by partial amorphization in a later thermal event). The relation between glass and the high-pressure
mineral in Muonionalusta samples should be studied in more detail (preferably down to the level of atomic resolution). The minor quartz indicated by the diffraction pattern might be a result of devitrification of the SiO2 glass over time.
A 2010 study reported the lead isotope dating in the Muonionalusta meteorite and concluded the stishovite was from an impact event hundreds of millions of years ago: "The presence of stishovite signifies that this meteorite was heavily shocked, possibly during the 0.4 Ga [billion years] old breakup event indicated by cosmic ray exposure...
Muonionalusta and Gibeon, both iron meteorites belonging to the IVA family.
The bulk of the data for nine troilite subsamples of Muonionalusta scatter with an apparent age of 4.57 Ga, which is shown to reflect the presence of both primordial and common terrestrial Pb components, in addition to radiogenic
Pb.
The most radiogenic subsample, however, has fractions with 206Pb/204Pb ratios as high as over 1000
and gives a statistically significant 207Pb*/206Pb* age of 4565.3± 0.1 Ma (MSWD=0.08), consistent with the 182Hf–182W metal–silicate segregation age of 2.4± 2.0 Ma. These data make the age of Muonionalusta the
oldest documented yet for all differentiated bodies in the Solar System and constitute the first high-precision
Pb–Pb age determined for crystallization of a phase contained within an iron meteorite group, hence
advancing our understanding of early Solar System chronology.
The isotopic composition of Pb in Gibeon troilite yields a significantly younger age of 4544±
7 Ma (MSWD= 1.5), consistent with evidence from the 107Pd–107Ag chronometer, but we believe this
age has been reset by melting upon shock. One puzzling observation is that the apparent 232Th/238U of
Muonionalusta troilite is particularly low (~0.32), requiring a mechanism capable of efficiently fractionating
Th from U, presumably the reduction of U to its trivalent form or the crystallization of phosphate.
The IVA group is also known for its broad and somewhat controversial range of cooling rates, between 30 and
6600 K per Ma (Rasmussen et al., 1995; Haack et al., 1996; Wasson and Richardson, 2001; Yang et al., 2007, 2008), which has been interpreted as the disruption and reassembly of the core of an early
planet 5–200 km in diameter.
Because of its large range in Pd/Ag ratios, Gibeon, which belongs to the IVA group, has become the reference for 107Pd–107Ag ages (Chen and Wasserburg, 1990; Schönbächler et al., 2008). Muonionalusta is
another, but less well known member of the IVA group, with large fragments excavated in Sweden from north of the Arctic Circle.
It is an octahedrite that contains large, cm-sized inclusions of troilite(Lagerbäck and Wickman, 1997). The presence of stishovite signifies that this meteorite was heavily shocked, possibly during the 0.4 Ga
old breakup event indicated by cosmic ray exposure (Voshage, 1967; Lavielle et al., 1999) and the associated shower (Holtstam et al., 2003).
The Pb–Pb dating of troilite inclusions from two separate samples of Muonionalusta and the implications of their ages for the early history of the Solar System is the main focus of the present work, although we also show Pb–Pb isotope data for a troilite inclusion from Gibeon, and Hf–W isotope data for Muonionalusta iron.
Two large samples of Muonionalusta (thin slabs, one rectangular and one triangular, of ~350 g each measuring, respectively, 8 × 10 × 0.7 cm and 12 × 14 × 15 × 0.3 cm) were acquired from an anonymous German meteorite dealer (the rectangular slab hereafter referred to as ML1) and from Luc Labenne, a French meteorite dealer
(the triangular slab hereafter referred to as ML2). Each slab contained a single large troilite inclusion, one only slightly elongated, the other ellipsoidal, with dimensions of about 3.5 × 2 × 0.7 cm (ML1) and
6 × 3 × 0.3 cm (ML2). The following sample characteristics are largely reproduced from the descriptions by Buchwald (1975) and Holtstam et al. (2003) of different pieces of Muonionalusta. The iron shows a
fine Widmanstätten pattern with long kamacite lamellae. Wasson and Richardson (2001) reported an average Ni content of the iron of 8.48 wt.%. Troilite varies from schreibersite, with the composition
of Fe0.97Cr0.02S, to kamacite near the edge, with the composition of Fe1.56Ni1.44P. The troilite is accompanied by subhedral grains of chromite, elongated grains of daubreelite (Fe2+Cr2S4), and rarestishovite, all up to 100 µm long.
A 120 g piece of Gibeon in the form of a thick slab measuring
5×4×1.2 cm with half of a single large, nearly circular (3.5×3×1.2 cm)
troilite inclusion comprising about a third of the iron meteorite sample
also was obtained from Luc Labenne. The troilite inclusion itself
contained small (~0.5 cm) spherical metal blebs scattered within the
sulfide matrix with a conspicuous metal-sulfide eutectic rim. From the
detailed petrological descriptions given by Buchwald (1975) and
Teshima et al. (1986), the two meteorites, Muonionalusta and Gibeon,
and their troilite inclusions, are similar, with the sole difference that
stishovite has not been found in Gibeon troilite. Teshima et al. (1986)
argued that Gibeon underwent some event of flash heating followed by
rapid cooling. Wasson and Richardson (2001) report a range of Ni
content in the metal of 7.9–8.2 wt.%.
Several troilite subsamples (nine for Muonionalusta and one from
Gibeon) in the form of massive chunks (1.6–3.5 g) were extracted
from the troilite inclusions of the two slabs of Muonionalusta and the
single slab of Gibeon using a stainless steel chisel. One of the
Muonionalusta subsamples and the Gibeon sample were first
analyzed on an Element 2 LA-ICP-MS at Rice University to verify
their true troilite nature and determine their depletion levels for Pb, U,
and Th. As expected, high concentrations of Fe, S, Cr, and Ni (of the
order of wt.%), as well as Mn, Co, Cu, P, and Zn (of the order of ppm),
and very low concentrations of Pb, U, and Th (of the order of ppt to
ppb) were found (Table 1).