[meteorite-list] Mohr's value for stoney meteorites

[MexicoDoug at aol.com]

Walter N. wrote:
<<I cut and polish stones and use a 6in diamond  trim saw for my work. The 
trim saw is rated to about a 6.5 Mohr's.  What is  the appox. Mohr's of common 
NWA's. I want to slice a few open to see what  treasures may be inside, but I 
don't want to ruin a 25 blade doing  it.>>
 
Hola Walter and welcome to the club !
 
That is a question that gets asked every once in a while.  But if  you think 
about it, it doesn't really make any sense.  You still  might ask, though, 
¿Are there any 6" blades to recommend for meteorite  cutting and any special 
measures to take with them?  The answer is  yes!
 
Pro-Slicer Blades are the way to go -v is something I learned by  osmosis 
from several listmembers including the kiwi NWA chop-shop king  who puts up with 
way to many snide comments considering his skills  at doing precisely what you 
want to do, as well as the modest and  ingenious "Corner" guy who writes for 
meteoritetimes.com.  Pro-slicer has a  version called "Gorilla" that works 
best albeit having a  thicker footprint(kerf).  These are highly recommended and 
all blade  must be used with some cutting fluid - either DISTILLED water (NOT 
CHLORINATED  TAP, NO, NO) or better yet 90%+ ethyl or isopropyl alcohol.  Some 
use  70% but in my opinion it would be better to used distilled water than  
that.  You really should use oven drying following a pure alcohol  bath.  That 
is what separates the men from the boys and in many cases the  quality from 
the mediocre.
 
Here is a link to get you started for your arbor design.  
_http://facetingmachines.com/sawsandblades.shtml_ 
(http://facetingmachines.com/sawsandblades.shtml) 
 
Probably any blade will work once, and some even better.  But if you  have 
several cuts to make, Pro-slicer is the way to go at $30 - $40 a blade  retail 
and $10 less wholesale.  Of course other blades including the one on  you saw 
could be just fine and  maybe MK's might last even longer, but when  you look 
at what you pay per cut you'll see what the fuss is  about.

Good luck.  For NWA chondrite a MINIMUM kerf of  0.012" is favored (and for 
NWA's 0.019" put up with happily for the  Gorillas).  It is when you get to 
real high valued stuff that the 0.009 to  0.006 kerf range starts to catch on due 
to their flimsyness and all that that  entails.  Of course your jig/vise 
setup will determine if you can slice  your meteorite like a deck of identical 
pepperoni slices or just cutting a lime  in half.  But you probably are a master 
in that department.
 
Back to your original question: the hardness of a meteorite for purposes of  
a "rated" hardness blade...IMO forget about it, nothing EVER works like they 
by  the numbers in this department, unless they say it plain doesn't  work.  
But please do recall that your beautiful NWA's are "concretions" of  the early 
Solar system.  They have flecks of iron (5.5), rusted areas(?),  almost quartzy 
silicate (7-) parts and an occasional even harder shocked  part.  To figure 
out a mean hardness of passing a blade through this solid  frozen genesis 
cocktail with all the variety of hardnesses and then to  generalize it...hmmmm I 
know the answer though I can't support it.  It will  be just hard enought to 
wear out your diamond saw blade just a little faster  than you are happy about,,, 
 PS don't buy meteorite CBN blades by almost  all those who have been there 
and done that...
 
Saludos, Doug