[meteorite-list] Sikhote-Alin details and thumbprints

[bernd.pauli 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