Thread: A meteorite fell on earth (really)

"If it's radioactive, then it's not a meteorite.
Only the thorium-rich lunar meteorites like SaU 169 are slightly radioactive when tested with a Geiger counter."

http://www.meteorites.wustl.edu/realities.htm

The ADS database contains the full text of several articles describing
laboratory analysis to measure radioactivity of specific meteorites,
including one (Kobe) which was studied less than 24 hours after it fell.

The reality is that this induced radioactivity caused by cosmic ray
exposure is very, very weak, requiring bulky and sophisticated laboratory
instruments to measure it at all. I cannot imagine that a hand held geiger
counter held next to any meteorite would give an indication above
background, even for a freshly fallen meteorite.

In the articles which I looked at, none of the radioactive isotopes
measured indicated an intensity of more than 100 dpm/kg (disintegrations
per minute per kilogram of sample), and very low values of less than 10
dpm/kg were more typical of short-lived isotopes such as 28Mg and 57Ni. By
comparison, the radioactivity of ordinary seawater is approximately 750
dpm/kg, attributable mainly to naturally occuring potassium-40.

To give an idea how far these levels are from acutely dangerous levels:
pure radium, which IS dangerously radioactive even for a brief exposure,
has an activity of 2.22 million billion dpm/kg. Madame Curie would have
undoubtedly lived longer if she had studied freshly fallen meteorites
rather than radium.

Since ALL natural objects are somewhat radioactive, the question "Is it
radioactive?" is not very useful. Even the much better question "Is it
dangerously radioactive?" is not always easy to answer with a simple yes or
no without knowing details of the nature of exposure (non-contact, skin
contact, ingestion, dust inhalation, etc.) and length of time exposed
(seconds or decades?). For meteorites, it seems that one can safely answer
"No more danger than common household objects."

http://www.mail-archive.com/meteorit.../msg00731.html

Meteorites are not radioactive
Meteorites likely traveled in space for millions of years before visiting us here on Earth. They were bathed in cosmic rays, but are not dangerous or radioactive. Some meteorites, such as Canyon Diablo from Arizona, contain micro diamonds but those gems are nearly invisible to the naked eye and can only be seen after cutting a specimen. To the best of our knowledge meteorites do not contain emeralds, gold (except possibly as a trace element), miniature fossilized aliens, insects from Mars, or common earth minerals such as quartz. If your rock looks just like other earth rocks, it probably is one. Meteorites look and feel different from the ordinary rocks around them.

http://www.aerolite.org/found-a-meteorite.htm

Radioactive is a "relative" term and oft misunderstood. A half cup of Brazil Nuts gives off more ionizing radiation than the daily maximum allowed for US nuclear workers. If you have a bed partner, you get more radiation from your partner's body than you do from all other sources--on the average. Every naturally occurring element has been identified in meteorites. This includes the ones we usually think of as radioactive and all the radioisotopes of the ones we don't think of as radioactive. Those isotopes missing would be those which have such short half lives that they have all decayed in the eons since formation. Meteorites do have trace, induced radio-nuclides which are of scientific interest as they tell us something about the length of time a meteoroid has been in orbit and subject to cosmic rays. Cosmic ray tracks tell us how deeply a section of meteorite may have been buried. Parent -daughter nuclides tell us how long since the meteorite solidified. However, to date, no meteorite examined has been found as radioactive as, a radium face place from an old alarm clock or a gram of Thorium or Uranium. If a suspected object shows a high count per minute (CPM) be suspicious of a plutonium power pack from a satellite.

http://www.geocities.com/a_machiz/Me...radioactivity?

Are meteorites radioactive?

No. Meteorites do contain radioactive elements, however, not significantly more than any ordinary terrestrial rock.

How old are meteorites?

Meteorites from asteroids are around 4.5 billion years old. Meteorites from the Moon are older than 2.5 billion years and meteorites from Mars may be as young as 65 million years.

http://www.nhm.ac.uk/nature-online/s...faq/index.html