The Sikhote-alin Meteorite
The Sikhote-alin meteorite is the largest observed meteorite fall in modern history. It rained a shower of fireballs into the thick forest of the Sikhote-alin Mountains in Eastern Siberia of Russia on February 12, 1947 at 10:38 hours. The flaming fireball, as bright as the sun, cast moving shadows in broad daylight as it passed by observers. It is estimated that over 23000 kg fell that morning leaving a smoke trail which could be seen in the sky for hours. The meteorite impacted the mountains with a huge explosion which was felt over 100 miles away. The impact made over 120 craters of varying sizes. The largest reported crater was 20 feet deep and 85 feet across. When the main mass exploded, it blasted fragments in every direction. Pieces were even found embedded in nearby trees.
There are two types of Sikhote-alin Meteorites: sharp, jagged shrapnel type specimens and the more beautiful individuals covered in regmaglypts. These magnificent thumbprinted specimens display a beautiful steel-blue fusion crust. The appearance of Sikhote-alin individuals is typical of what the general public believes a meteorite should look like.
The "shrapnel type" or fragments of Sikhote-alin are the result of violent explosions that occured close to the ground as the fireball came through the atmosphere. These specimens were too close to impact to have time to benefit from atmospheric heating.
The most desirable type are what have become know as an "individual". Due to atmospheric heating and ablation, these specimens developed regmaglypts, ore what is commonly called "thumbprints".
Sikhote-alin is classified as a coarse iron octahedrite type IIB. It displays a beautiful pattern of Widmanstatten lines when sliced and etched. It is the amount of nickel relative to the amount of iron present that creates this crystalline pattern. This pattern is only present in etched meteorites and is one way of determining the authenticity of a suspected meteorite find.
Some of the small individuals have a smooth appearance and did not form regmaglypts from the atmospheric heating and ablation. Many collectors seak these out.
The rarest type of Sikhote-alin meteorite (or any meteorite) is the oriented specimen. Meteorites that remain in a stable position during their atmospheric entry take on characteristics which are unique to this process. The major characteristics of an oriented meteorite are flow lines in the fusion crust, a flowing appearance of the metal itself on the leading edge, well define oval regmaglypts or completel smooth on the back with a well defined roll-over rim along the edge of the back where the metal and fusion crust flowed onto the back edge as it melted away. Specimens can have one or all of these features and be termed as oriented or flight marked. The term flight marked is used when the specimen does not have an obvious direction of entry.
The Sikhote-alin strewnfield has been hunted very aggressively since the fall of the Soviet Union. I personally have been acquiring specimens from Russian suppliers since they started recovery. The hunters have been telling me for several years now that the hunting results have been less and less every season and the area is now nearly hunted out. It is my personal experience that what they have been warning me about for years is now painfully true. High Quality Sikhote-alin meteorites are getting extremely difficult to purchase from Russia now and the prices have been rising steadily.