[meteorite-list] Cutting with water soluble oils?

[MexicoDoug]

Erik asked:

"Is it okay to cut chondrites with water soluble oil in an oil saw or 
will that screw with the classification?"

Hi Erik,

The question seems to ask if the classification of a chondrite can be 
changed by getting it soaked in a water-soluble solvent.

No, I really doubt it would alter the classification, so in that sense 
it would be fine.  But ...

... the next question might be, is this a good idea, anyway and you 
have some good answers to that already.  Further, if we assume the oil 
will be dipolar as well as hydrocarbon soluble at the same time, you 
definitely don't want to use it on any *carbonaceous* chondrites as you 
could leach out some interesting components of the meteorite and throw 
it away with the waste-solvent.

If it is basically an *inorganic* (i.e., *not carbonaceous*) chondrite 
there isn't much risk in my opinion in the near term if you use a clear 
oil.  The trouble could come into play in the near term if it is heat 
dried, where some oils are subject to low temperature browning ... and 
then over the long haul since the slice will last at least another one 
billion years the oil can decompose all by itself and color the 
meteorite which I think was the gistof another answer you had.

The use of water as a solvent has two competing ideas.  First, since 
the air is loaded with water, it is like you are adding nothing to the 
meteoritethat wasn't already their except a quick liquid dip which most 
chondrites have already experienced anyways.  But that competes with 
the idea that the liquid can transport contaminants such as oxidants 
and rust catalyzers into the interior - and we've all see how some bad 
cut jobs start showing leopard spots.  So that covers the optimal trade 
off of deionized water (or distilled water which is usually better if 
 from the same vendor since it also removes uncharged atoms and 
molecules disolved in the water as well).

But really soaking will alter the leachable mineral concentrations of 
an inorganic meteorite too, though unless you are very specifically 
looking for the pristine ratios, it makes virtually no difference for 
chondrites that have been sitting in the desert.

That leaves the least invasive option of all.  Dry cutting.  But before 
we pat ourselves on the back for having better methods than the King 
lab, don't forget that a saw blade wears out more quickly dry causing 
plenty of particles that will get all over the specimen anyway, since 
the heat and no lubrication causes the welding of meteorite particles 
to the sharp cutting piece tips on a microscopic level, leading to 
their fracture and degradation of cutting properties - and many of the 
hard cutting substances are carbon-based.

But what about a pure silicon based oil like a heat stable one maybe - 
no clue.  I don't know if they are used for cutting but it sounds lke 
an expensive project, for our favorite silicates ... can't win ;-)

Kindest wishes
Doug