Low Iron Meteorites

[Goldfinger]

Hi Everyone:

I've been thinking about a little project concerning meteorites but have a question about low iron meteorites in general. As you all know, the rust is formed from oxidized iron within the meteorite itself. Would meteorites that have a LOW iron content show rust if found in a wetter enviorment like in the Midwest? In other words- do the L,LL, and other low iron content meteorites show the same rust stains as the ones with a higher iron content? I've never seen any pictures of low iron meteorites with rust but maybe that's because they have a fusion crust or were found in the desert.

Steve

[John B.]

Hi Steve

If you would like to see an L chondrite with a lot of rust staining but still free metal look on Bills meteorite web site. The small slice of Triliby Wash piece he is holding has a bright red stain. Yet some of the material that was well crusted from the larger pieces has a nice cream white silicate matrix. Many of the L and H chondrites that we found in Oman were void of free metal leaving only tiny rusty pits were the metal once was when cut. In Oman the rain fall is almost nonexistant but fog is fairly common. Saturating only the surface rocks and soil. As the moisture permiates through any minute fractures within the stone crust it becomes trapped within and daytime heating probably helps the rusting process. I'm reasonably certain that many of the Omanie strewnfields are newer than Gold Basin or Franconia yet weathered worse than them . There are some studies that were done on preservation of meteorites by soil lime and lime carbonate content and since Gold Basin aged at 15,000 plus years it has obviosly survived the last Ice age (roughly 10-12k years ago) where the Gold Basin area was a similar climate to Wisconsin. The german scientists doing the study propose the the lime carbonate soil leaches the moisture from the specimens on the suface or shallowly buried and helps to inhibit rusting !! There are charts that equate weathering grades with age dating which are only a guide and in real life in most cases aren't even close because of the variables in preservation. But since terrestial age dating is a lenghty expensive process it's rarely done on finds. I don't know how they classify the iron content of the weathered material into LL-L-or H condrites when the free metal may be rusted away ?? But I'm certain they have a way since they do it ?? Steve I have a couple of 25 lb door stops that are Wolf Creek Western Australia Irons. I haven't cut them (my 10 inch saw is tooo small) but I'm told they are shale balls. They are Octahedrites with a terrestrial age of 500,000 years old roughly 10 xs that of Canyon Diablo's 50,000 years. All the iron has rusted away and replaced by silicates . They are slightly magnetic and yep I beeped em at depth with my goldmaster. I doubt a pulse induction would hear em if so it would be subtle !! I think :confused0013: ?? Happy Huntin John B.

[Goldfinger]

Hi John B:

Thanks for all the info and the explanation. It took awhile to digest everything you said in the reply and it proves I still have much to learn about meteorites. :spinnin: Do you think it would be possible to to beep a meteorite with a detector and yet have absolutely no attraction to a magnet?

Steve

[fredmason]

I am assuming you are asking anyone, so....

if the detector is ground balanced to the soil, and if the meteorite is sufficiently different it "may" respond as either a hotrock or coldrock...however the signal will likely be very faint. However,I doubt you would get any signal at all from any PI machine...I yield to the fine gentleman from the border country, MR B.

Fred

[John B.]

Hi Steve

Almost certainly ordinary chondrites and most achondrites would have to maintain a realatively high iron or iron oxide contents to be magnetic therefor they would probably be audible on good vlf detectors. The same for planetary material namely basalts. But I think it may be possible for carbonacious chondrites to be audible yet not magnetic. I ain't found any so I'm uncertain about that ?? However they may have enough carbon to give a decent response on a good vlf yet not have enough iron to be magnetic. Anyone who's done enough vlf beepin has dug burnt shrub stubs and old campfires which also seem to give pi machines some noise as well. I don't know the reasons why carbon seems to react that way but I'm certain there is some explanation for it. I think :hmmmmmm: ?? Happy Huntin John B.

[John B.]

Hi Fred

You are very correct !! I was gonna add that point as well !! An LL chondrite on a bed of blacksand may not make a response on the most sensetive detectors !! I think :confused0013: ?? Happy Huntin John B.