[meteorite-list] Sikhote-Alin details and thumbprints

From: bernd.pauli at paulinet.de <bernd.pauli_at_meteoritecentral.com>
Date: 18 Feb 2007 22:09:28 UT
Message-ID: <DIIE.000000BC00001728_at_paulinet.de>

SA specialist and photographic artist Geoff N. wrote:

"As we know, the average size of thumbprints on Sikhote-Alin
individuals increases in proportion to the size of the individual."

In other words: if you have a piece in your collection whose regmaglypt
size correlates with the specimen's size, you can be relatively sure that
you have a piece that was not spalled off a larger mass. If the thumbprints
are too large with regard to the specimen size, it fragmented from a larger
mass.

But how do you know? Well, just divide the average regmaglypt diameter
by the size (length) of your specimen. According to Buchwald, you should
get this:

"The ratio between the diameter of the regmaglypts and of the fragments ranges from
0.05 to 0.25, with the majority giving 0.08-0.10, for specimens 5-45 cm in size."

Reference:

BUCHWALD V.F. (1975) Iron Meteorites (UCLA, 1975, Vol.3, pp. 1123-1130).


BUCHWALD V.F. (1975) Iron Meteorites
(Univ. of California, 1975, Vol.1 , p. 18 / Vol. 3, p. 1126):

Date of fall: Feb 12, 1947
Time: 10.38 a.m. (local time)
Direction: N => S (10-15? east of north)
Initial inclination: 41?
The initial declination had increased to 60-70? at the time
of impact (zenith angle about 49?).
Apparent diameter of the bolide: 600m (with its luminous envelope).
Length of smoke trail: 33 ? 9 km
Dust trail observed for several hours.
Brightness of bolide: exceeded that of the sun (about - 26)
Point of complete breakup: 4 - 6 km (Hemmungspunkt)
Initial velocity: 14.5 km/s
Geocentric velocity: 9.2 km/s
Heliocentric velocity: 37 km/s
Preatmospheric mass: 1000 t
Radius of light and sound phenomena: 300 - 400 km
Largest fragment: 1.745 kg
Specimens collected: 8.500
Total weight: > 23 tons
It is estimated that a total of 70 tons fell, including dust.
Impact holes: 122 (? 0.5 - 26 m/ 1 - 12 m)
Scatter ellipse: 1.6 km^2 ( N => S = 2.1 km /E => W = 1.0 km )
A smaller ellipse of 0.75 x 0.30 km was found to exist.
Final velocities: 0.1 - 1 km/s


Best wishes,

Bernd
Received on Sun 18 Feb 2007 05:09:28 PM PST