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

From: MexicoDoug_at_aol.com <MexicoDoug_at_meteoritecentral.com>
Date: Sat Jun 24 02:57:43 2006
Message-ID: <521.17093b8.31ce3c63_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
Received on Sat 24 Jun 2006 02:57:39 AM PDT