ARN's Guidelines to Meteorite Classification
©2006 2012 Astronomical Research Network Ken Regelman
206 Bellwood Ave.
Maplewood, MN 55117 USA
FIRST I want to thank the meteorite community
for all the help I have gotten that made this work
possible . The NAU, Washington University, the many books and scientific papers and the people
to many to mention that I would not want to favor one over the other . So I leave there names out
but they know I am great full for all the help and suggestions made so far . Thank you All !
I hope that the meteoritical community can work together to standardize the classification of Meteorites !
I hope to put down in print for the first time ever these standards .
This is an on going work as the meteoritic community reviews this work I am sure there will be additions
and changes . I encourage your feedback to help make this work as accurate as possible .
If all you have to SAY about this work is complaints move on this is a hard task with no help !!
Thank You Kenneth L Regelman / ARN
There are many links not yet finished , keep watching for more to be added
1. Classification of Type eg. chondrites, Carbonaceous ,Lunar etc.
The most difficult task is to properly identify a meteorite and it's proper type.
In the following pages I hope I have given you the Guidelines to do that .
2. Shock grade
S1: completely unshocked; (up to 5 GPa)
S2: very weakly
shocked (5-10 GPa); uneven darkening of olivine as seen under
planar and irregular fractures, (breaks in other than a natural cleavage plane)
weakly shocked (15-20 GPa); weak fractures in olivine seen under
dark shock veins and some melt pockets
moderately shocked (30-35 GPa); weak planar fracturing of olivine
under polarized light;
some pockets of melted material, dark interconnected shock veins)
strongly shocked (45-55 GPa); very strong planar fracturing and
deformation features in olivine;
alteration of plagioclase into maskelynite; formation of dark melt veins
strongly shocked (75-90 GPa); olivine recrystallizes, with local
alteration to a mineral called
ringwoodite and shock melting of plagioclase to a glass
Ringwoodite is an altered crystalline form of olivine
Greater shock pressures will melt the rock, producing what is referred to as an "impact-melt".
The fracturing of olivine crystals and other features must be observed under a microscope with shock effects
observed under polarized light. Larger structures, such as shock veins are visible to the eye.
Many of the shocked veins formed at the boundaries of polished surfaces of brecciated specimens exhibit
beautiful spider-web-like structures.
3. Weathering grade
W0: No visible oxidation of metal or sulfide. A limonitic staining may be noticeable in transmitted light.
W1: Minor oxide rims around metal and troilite; minor oxide veins.
W2: Moderate oxidation of metal, about 20-60% being affected.
W3: Heavy oxidation of metal and troilite, 60-95% being replaced.
W4: Complete (>95%) oxidation of metal and troilite
W5: beginning alteration of mafic (iron/magnesium) silicates
W6: massive replacement of silicates by clay minerals and oxides.
4. Breccia definitions
In describing a meteorite it may be necessary to describe its
Brecciated structure .
Consist of fragments of one chemical-petrologic type
Consist of fragments of one chemical group but with more than one
petrologic type .
Consist of fragments of more than one chemical group but and more
than one petrologic type . Polymict breccia are meteorites within
meteorites eg H3-
5. Sample Donation size
At this time the Meteoritical society requires that any new meteorite being classified have
20% or 20grams which ever is smaller be donated to the institution where the material
is accessible to researchers wishing samples for further studies .
6. When you are certain you have all the data to submitt a correct classification this
Form is Sent to the Nomenclature Committee of the Meteoritical Society for official recognition .
7. Picture data base
This is an option now but I highly recommend taking a digital picture
of every meteorite being classified .
Procedure / steps to classification to the Meteoritical Society
1) A new meteorite is characterized in the laboratory
2) The information is submitted to the Nomenclature Committee, usually to
one of the Associate Editors (AEs), but sometimes directly to the Editor.
3) The AE acknowledges receipt of the information and tells you that all is
4) The AE transfers the information to the Editor of the Bulletin.
5) The Editor assembles information on all meteorites sent in by the AEs
and sends it to the entire NomCom for a vote.
6) The Editor receives the votes and decides if each meteorite has been
approved. The appropriate AE is informed of the decision.
7) The AE tells you either (a) the name is approved or (b) the name did not
8) For approved meteorites, the text or information you submitted is
eventually edited for publication. You may get an advance copy of this
text, but sometimes not. A provisional Bulletin may appear on the
web. All text at this stage is subject to further revision.
9) The Bulletin is submitted to MAPS for publication. At this point, all
entries are final and can be quoted directly, without qualification.
Your meteorites are at step (4). They have not been approved OR sent out
for a vote. The AE has simply accepted your submission and sent it to the
Editor. Therefore, you cannot say that the text you quote is approved by
the NomCom, nor can you say it will appear in the Bulletin. That depends
on passing step (7). All you can say is that your text has been submitted
to the Bulletin.
Meteorite Testing Labs
http://www4.nau.edu/meteorite/ Specializing in Achondrites