Monday, April 27, 2009

Tektites Rock! How to Find and Collect Tektites

You've probably heard of that asteroid tracked to it's explosive demise over the Sudan desert in 2008 (fragment shown at left). Only a few meters across, it didn't survive intact and shattered before it hit the ground, sending hundreds of debris strewn on the desert sand. Eventually, fragments of the doomed asteroid were recovered. It was easy because astronomers knew where it went and it also left fireball dust like in the following picture left behind by the Almahata Sitta fireball.

A lot of meteorite collectors would have scrambled to get a piece of Asteroid 2008 TC3 if they also knew where to look. But the fact is that meteorites are quite difficult to find. Usually, scientists look for them on ice fields, where they stand out starkly against the white ice. Others prefer vast stretches of sandy desert, where they also stand out like sore thumbs. But of course, not everyone has the means to travel to the North Pole or the Empty Quarter of Saudi Arabia just to hunt to meteorites.

The next best thing to collecting such souvenir rocks from space is to simply collect tektites (top pic from Tektites, of course, are rocks that are the result of asteroids that have impacted Earth in the past. thrown high above the atmosphere as molten globs that solidified, they form strange shapes upon reentry into the atmosphere since they are melted again. They drop to the ground, on what are called strewn fields, as odd rocks that do not match others on the ground.

Here is a table of major tektite strewn fields in the world:

(million years)
Australasian Australia, Tasmania, Indonesia, Philippines, and most of Southeast Asia
Czechoslovakian Czech Republic 14.8
North American Texas, Georgia, Martha's Vineyard, Cuba 35
Ivory Coast Ivory Coast of Africa ~ 1.0
Libyan Libyan Desert 28.5
Irgiz North of the Aral Sea 1.07
Aouelloul Mauritania (West Africa) 3.5

If you live in a country or in a specific area that's part of a major strewn field, then you're lucky, because the chances of you finding tektites is high. In the Philippines, for instance, tektites are regularly collected and sold as amulets in Manila. People simply go and walk by the side of rivers and over fields to look for them. They are simply visually sorted out and picked up by hand from the other rocks on the ground. Most are small - an inch or two, but some can be as big as five inches in diameter or even more, although these big tektites are rare. Dr. Henry Otley Beyer (left), the renowned American anthropologist who lived with the Ifugaos, did most of the collecting of Philippinites. His collection now forms part of the National Museum displays, including those at the Planetarium at the Luneta park.

Of course, you have to know what tektites look like in order for you to find them. Most are dark and grooved, but others, like Libyan desert glass (left), are translucent and appear shattered. You can see samples of how tektites look here in this entry in Wikipedia. There you'll also see how some rocks like sandstone can have the shape, but not the texture and color of a tektite.

FACT: In the Philippines, tektites were once collected in Ortigas in Metro Manila. Today, there are the Tektite towers that stand along Exchange road to remind us of the richness of the area for tektites! You can check out one of the abstracts of the research papers where a find in the Ortigas site is mentioned, here at the SAO/NASA Astrophysics Data System. Just type the words "tektites" and "ortigas" together and you'll find it.

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