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Schoner's  

Meteorite Identification Page

Page 6 

4 ) Is it solid, and lacking bubble holes?

Meteorites very rarely ever have bubble holes (vesicles or vugs). But there are a few exceptions, and one of these if it had not been an observed fall would have been discounted as a meteorite. So, if the rock has large holes all over it, and also inside a broken surface, then the chances of it being a meteorite are very, very remote.

 

5 ) Does the exterior of the stone look smooth, or have rounded edges? Does it have what look like shallow "thumbprints."

These are characteristic features of most freshly fallen meteorites, as well as many finds that were not witnessed to fall. During the hypersonic phase of the meteoroid's passage through the atmosphere as a meteor, surface temperatures are so extreme that the rock vaporizes. This vaporization is so violent and quick that very little if any heat travels into the interior of the stone, or iron before it is vaporized away. In other words, the meteoroid is vaporizing faster than heat can conduct into it. This is similar to effect to thrusting a chunk of ice into and out of a blast furnace. If the block of ice is large enough a piece of ice will survive. Likewise, the rock or iron that survives the fiery passage through the earth's atmosphere often arrives on the ground at a temperature very close to what it was when it was in space. And this is usually ice cold, but often slightly warm to the touch, especially if it fell during the daytime.

Contrary to popular belief, most meteorites do not arrive onto the surface of the earth burning. The burning fireball phase (bolide) usually terminates 15 to 20 miles above the earth, and the rock simply falls to the ground just as a solid object would if dropped from a high altitude. Compared to the spectacular celestial display meteoroids cause as their cosmic velocity is slowed during the bolide phase, the actual arrival of a meteorite on the ground is usually accompanied by nothing more than a thud and a small impact pit.

Fortunately, our planet's atmosphere slows most meteoroids down enough so that true crater forming events are rare. But for freshly fallen meteorites the surfaces of such often display a texture that is clear evidence of a fiery passage through the atmosphere. Edges are somewhat rounded, and any broad surfaces often have peculiar markings called "thumbprints" (as if the rock were plastic and someone picked it up).

 

 

Glorieta Mountain, NM; Siderite (iron), 658 grams. Notice the "thumbprints" on this exceptionally beautiful specimen. Also present are traces of blue-black fusion crust. A space rock like this is too nice to cut or grind. But inside it looks like steel.

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