[meteorite-list] Question for type collectors

[Galactic Stone & Ironworks]

Hi Jeff and Michael,

Thank you for the input.  I think what I will do is subdivide my type
list into two arbitrary categories - irons and everything else.  So I
will treat irons seperately.  I will maintain my "petrologic type"
count for stony, stony-iron, and everything else that doesn't fall
under "irons".

I asked all of this because I like to have a record of the various
aspects of my collection - just in case someone asks me questions like
- "How many lunars do you have?" or "How many types do you have?", or
"How many witnessed falls?" , etc.

Plus I am a statistics geek and I like to have everything in my
collection accounted for and broken down to the Nth degree. ;)

I have yet to break down my collection by country - that will come
tonight.  I need to do it now while my collection size is still
manageable.

Best regards,

MikeG


Here are some of the revised stats now -

29 witnessed falls, 55 finds - 84 total localities

29 witnessed falls
14 hammer falls (3 hammer stones)

42 petrologic types
  5 iron types - IAB-MG, IIIAB, IVA, IAB-ung, unclassified (Las Palmas)

7 continents
18 USA falls and finds
10 US states - Alabama, Arizona, Connecticut, Georgia, Illinois, Iowa,
Kansas, Louisiana, New York, Texas
28 NWA finds

7 planetaries (3 Lunars, 4 Martians, 8 Vestans)

47 specimens  <1 gram
27 specimens  1-9 grams
12 specimens  10-99 grams
2 specimens     >100 grams


.................................................................

On 4/15/09, Jeff Grossman <jgrossman at usgs.gov> wrote:

> "Petrologic type" is really a term that only applies to chondrites.  It

> was popularized in the classic paper:

>

> VAN SCHMUS W. R. and WOOD J. A. (1967) A chemical-petrologic

> classification for the chondritic meteorites. Geochimica et Cosmochimica

> Acta 31, 747-765

>

> The term was meant to convey a sense of the degree of equilibration of

> chondrites.

>

> In the old days, there were only 6 defined petrologic types (1-6),

> making it easy on a collector or museum wishing to establish a reference

> collection.  But now, the scale is interpreted more continuously, with

> nearly 30 subdivisions appearing in the literature in one place or

> another (1, 2.0-2.9, 3.01-3.05, 3.10, 3.15, 3.2-2.9, 4, 5, 6), as well

> as transitional types like 1/2, 3.6/3.7 or 4/5, and breccia mixtures

> like 4-6..

>

> As for nonchondritic meteorites, petrologic type is undefined.  For some

> of these, there are groups, like the groups of irons you mention, which

> are analogous to the groups of chondrites (H, L, LL, R, CV, etc.).  Some

> of these are themselves subdivided, as is the IAB complex.  For other

> achondrites, like mesosiderites, there aren't really groups defined, but

> they have been subdivided into petrographic classes and metamorphic

> grades, with designations like "B1" to show this.  HEDs and ureilites

> are really messy.

>

> Textural terms, like the iron structural types you mention, or terms

> like "polymict," "brecciated," etc., are not really classification terms

> (in general).  These are mostly descriptive terms.  Use these to

> subdivide a collection with caution, as they may not be applied

> uniformly to all meteorites by all researchers.

>

> Jeff

>

>

>

> Galactic Stone & Ironworks wrote:

>> Hi folks!

>>

>> I am not a type collector per-se, but I like to keep track of how many

>> different petrologic types I have in my collection.

>>

>> I have a silly question about type collecting -

>>

>> Do type collectors consider each type of iron a seperate petrologic

>> type?  For example, are all octahedrites considered 1 type?  Or is it

>> different types for "coarsest", "coarse", "medium", "fine", etc?

>>

>> Right now I have 42 petrologic types - counting ALL irons as only one

>> type.  Should I go through my collection and correct that count to

>> reflect the different types - IIAB, IAB, IVA, etc?

>>

>> Thanks in advance!

>>

>> MikeG

>>

>>

>>

>

>

> --

> Dr. Jeffrey N. Grossman       phone: (703) 648-6184

> US Geological Survey          fax:   (703) 648-6383

> 954 National Center

> Reston, VA 20192, USA

>

>

>



-- 
.........................................................
Michael Gilmer (Louisiana, USA)
Member of the Meteoritical Society.
Member of the Bayou Region Stargazers Network.
Websites - http://www.galactic-stone.com and http://www.glassthrower.com
..........................................................