[meteorite-list] Kalkaska

From: bernd.pauli_at_paulinet.de <bernd.pauli_at_meteoritecentral.com>
Date: Mon Aug 21 04:18:47 2006
Message-ID: <DIIE.0000006C00000B72_at_paulinet.de>

Hi George and List,

"I'm looking for any information regarding the Kalkaska find (Michigan, 1947,
medium octahedrite). An image of the main mass or perhaps its location would
be helpful. It's a stretch I'm sure, but you never know."

Here are some passages from Buchwald with regard
to the Kalkaska iron. Maybe this is helpful.

Best wishes,
Bernd


Kalkaska, Michigan, U.S.A.
44? 38' 49" N, 85? 08' 12" W

Medium octahedrite, Om.
Bandwidth 1.00?0.15 mm.
Group IIIA.
7.4% Ni, about 0.1% P, 18.1 ppm Ga, 33.5 ppm Ge, 11 ppm Ir.

HISTORY

A mass of 9.4 kg (20.7 pounds) was plowed up in 1947 or 1948 by A.R.
Sieting, about 10 km south-southwest of Kalkaska, in Kalkaska County.
The field had been cultivated for over 30 years, so the sound of the
cultivator blades striking metal was quite unexpected. The mass was
shown to various peoples and to schools, before it was presented, in
1964, to Michigan State University where it was described with a photo-
graph of the exterior and a photomacrograph by Chamberlain (1965) who
also gave further details of the find.

COLLECTIONS

Abrams Planetarium, Michigan State University,
East Lansing (main mass), Washington (759 g).

DESCRIPTION

The irregular mass has the approximate overall dimensions 18 x 15 x 9 cm,
and it shows numerous well developed regmaglypts 10-20 mm in size. Locally,
deeper holes are carved out, as for instance, 10 mm deep with an aperture
of 20 x 15 mm. The mass is covered by a brown oxide crust from terrestrial
corrosion, but the fusion crust may still be observed in various places.

Etched sections display a medium Widmanst?tten structure of straight, long
kamacite lamellae with a width of 1.00?0.15 mm ... the plessite fields are
degenerated and contain only little taenite.

Schreibersite is not common ... Rhabdites are present in many kamacite
lamellae, but they are small, generally less than 2 ? thick.

Troilite occurs as angular and lenticular bodies, ... frequently enveloped
in 0.5-1 mm swathing kamacite ... The troilite contains daubreelite as
50-200 ? wide bars that are often brecciated together with the troilite
itself.
Isolated daubr?elite, or possibly brezinaite, grains occur as angular
crystals, 10-40 ? in size, in the kamacite.

Veinlets of troilite extend into the metallic matrix, ... contain breccias
of troilite with minor amounts of daubr?elite that are set in a matrix of
terrestrial corrosion products. The breccia-filled fissures mainly follow
schreibersite-filled grain boundaries; it appears that the cracks were
created at a remote shock event and that shattered debris from the troilite
nodules partly filled them up. Open as they were, they became an easy prey
for percolating, terrestrial ground water.

Kalkaska is a shocked medium octahedrite which appears to be related to
Costilla Peak and Boxhole. It is a low-nickel low-phosphorus member of
group IIIA.

Specimen in the U.S. National Museum in Washington:
759 g slice (no. 3217, 10 x 5 x 2.4 cm)

Reference:

BUCHWALD V.F. (1975) Handbook of Iron Meteorites, Volume 2 , pp. 707-709.
Received on Mon 21 Aug 2006 04:17:17 AM PDT