[meteorite-list] Tatahouine Connoisseurs' Guide

[mexicodoug at aim.com]

Dear Listees,

As I went through my specimens of Tatahouine all night; I just got that 
old lovin' feeling all over again.  I thought I would share some 
personal opinions regarding this incredible green meteorite, with the 
benefit of having looked at several kilos of material over the years.  
They are personal opinions, though, so please understand opinions don't 
always agree.

Here's what I wanted to share:

There are incredible natural telltale impact signs of on Tatahouine.  
In general the locality should not be polished, as these valuable signs 
may be erased.  Of course some people may like to do this to enhance 
looks orundrstand shock veining, but my personal opinion, nice pieces 
are rare and contain the history of the meteorite written delicately in 
the tiny markings.  Like a quartz crystal, the meteorite can be 
cut...but...  At the mineral shows this is a common practice with big 
quartz to make faux crystals that look cool.  It's a personal decision. 
  Next, be wary of frequent claims of Tatahouine meteorites with fusion 
crust.  The same telltale signatures of crystal cleavage that show 
impact, also show it impossible for fusion crust to have formed in many 
places claimed with a little common sense.  Tatahouine crust is 
brownish-black, and very matte finished, and quite thick and a little 
crumb-like.  Don't ask me to explain crumb-like, that is just what I 
think when I see it.  And it's quite obvious once you've seen it one 
time.  If it is thin and shiny, and blue-black it is not what I 
consider fusion crust.  I believe it to be chromite and/or Iron Sulfide 
inclusions.  Whether they may have melted during entry or along crystal 
boundaries due to other energy inputs, no comment, just that the 
authentic fusion crust is completely differently textured.  But many 
will call this fusion crust.  For me this is almost a moot point, there 
is so little.  Though, whatever it is, it is a nice feature to have.  
But there are plent more much more interesting features once you get 
into it, that these shiny black features are no where near the top of 
my list.   But I would stress it is not fusion crust.  Fusion crust 
invariably occurs, when it so very rarely does, on a powdery surface 
which is smoothes (Don't clean or polish even if no crust!).  Other 
interesting features in Tatahouine are chromite inclusions as well as 
Iron Sulfide.  You can have a few specs of what looks to be metal 
flakes built right into the crystal lattice.  These are big crystals - 
the biggest of any stony meteorite to my knowledge.  I've seen one 6 cm 
long!  I just saw one specimen with a step-work lamilar crystal 
fracturare pattern that blew my mind, also another with a blob of some 
sort of metal contain gunk (or what - I don't know).  Even shattercone 
hairlines are pronounced in some specimens.

Did you know that the study of Tatahouine was what nailed the coffin 
shut on the Allan Hills 84001 meteorite not having fossil Martian life 
forms?  It's because the same structures were observed to have 
developed in meteorites recovered in 1994, compared to the original 
material recovered a short time after the fall...

Best wishes,
Doug