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Meteorite 101

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Meteorite 101 Cutting, Surface Preparation, Etching, and Preserving Iron Meteorites Prepared for AOAS By Leonard Lynch Introduction The purpose of this presentation ... – PowerPoint PPT presentation

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Title: Meteorite 101


1
Meteorite 101
  • Cutting, Surface Preparation, Etching, and
    Preserving Iron Meteorites
  • Prepared for AOAS By Leonard Lynch

2
  • Introduction
  • The purpose of this presentation is to teach you
    the basic steps in Cutting, Surfacing, Etching,
    and Preservation (Rust Prevention) of Nickel/Iron
    Meteorites.

3
Types of CutsSlices Slabs Slice
ShapesEnd Cuts and Windows
4
Continued
  • 3D Shapes
  • Jewelry and Coins
  • Knives Other Objects

5
Step 1 Cut The MeteoriteIron Meteorites are
usually cut with a horizontal band saw.
  • Though very efficient at cutting metal, the
    blades leave saw cut marks that must be removed.

6
ContinuedNote Window Cuts can be made with
the use of a Belt Sander alone. Using a belt
sander, work an area on one end, until it is
Smooth and Flat, then continue to step 3.After
you determine where you want to cut (Slices, End
Cut or Window), secure the meteorite in the saw
vise.A loose vise or slack saw blade can result
in very deep saw marks and uneven cutting that
can be hard to grind out. Carefully cut the
meteorite.
7
Step 2 Surface Preparation - Removing the Saw
MarksAs you can see from the photo above,
cutting a meteorite leaves obvious saw marks that
must be removed.The best way to do this and not
add to the surface marks or alter the surface
flatness, is to use a Table Top Belt Sander
8
ContinuedTable Top Belt Sander with 6
Vertical Disc SanderDo not use the Vertical
Disc Sander because it is too easy to gouge and
leave deep scratches from the edge of the disc,
that results in more sanding than would have been
necessary.
9
Continued Use the vertical belt sander to
remove the saw marks. I use a 80 to 120 grit
belt. Keep the meteorite orientated always in the
same direction on the sanding belt. This will
keep all sanding marks going the same direction
and easier to remove.Step 3 Hand
SandingWhen all of the initial saw marks are
removed, use a orbital/vibration hand sander with
progressively smaller grit sand paper. This will
give the meteorite surface a mirror finish.
10
ContinuedWith the hand sander try to keep the
surface of the meteorite level with the surface
of the sand paper. Avoid sanding the edge of the
meteorite. You do not want to round the
edges(Note be very patient. This step will
take a while...About 1 to 2 hours per grit of
sand paper.)I start off with 200 grit sand
paper. Sand the meteorite surface until all of
the visible belt sanding scratches are gone.
These scratches are easy to see and go in one
direction, if step 1 was followed. The hand
sander leaves smaller scratch marks. (Note Buy
sand paper that is made for use on metals, not
wood. It will last longer)
11
ContinuedNext use 500 grit sand paper. Use
this until all the scratches from the 200 grit
paper are gone. You will begin to see a mirror
finish develop on the meteorite
surface.....Next, use 1200 grit sand paper. As
before, use this paper until all previous sanding
scratches are removed. At this point the surface
of the meteorite should have a mirror like finish
with small vibration scratches. These are caused
by the vibration of the hand sander and can be
easily removed by using a piece of 1200 grit sand
paper by hand, on a sanding block, for about 10
minutes or so.
12
Step 3 Etching the MeteoriteFor this step,
you will need the following items and
materials 2 Flat, Shallow Plastic Bowls
Rubber Gloves 12 ounces of water 2 ounces
of Ferric Chloride (Etching Material) This is my
preference. A solution of Nitric Acid may be used
instead. Paper Towels
13
ContinuedCAUTION Ferric Chloride (or Nitric
Acid) can burn sensitive skin. Always were rubber
gloves during use. These chemicals will also
etch ALL metal surfaces. Ferric Chloride will
stain concrete and other porous materials such
as skin, clothing, wood, floor tiles or counter
tops. Be very careful not to spill or drip the
chemicals. Cover work area with Paper
Towels. Place the Plastic Bowls on the paper
Towels. Put on rubber gloves. Carefully
pour 1 to 2 ounces of the etch material into one
bowl and a few ounces of water into the other
bowl.
14
ContinuedNOTE If the meteorite has had oil or
another rust preventative (such as WD-40)
applied to the sanded surface, wash the meteorite
with dish washing soap and water to remove it.
Carefully place the meteorite, sanded surface
side down, into the etching material,
letting it set in the solution. After about 60
to 90 seconds, remove the meteorite from the
etch solution and place in the bowl containing
water. This will stop the etching
process. Remove the meteorite from the water
and inspect the surface.A good etch will bring
out the "Widmanstätten" pattern. This is
basically the crystalline structure of the metal
as a result of cooling over thousands to millions
of years. If a deeper etch is preferred, you can
go back through the etching process.
15
Continued Fine

Coarse
Widmanstätten Patterns
Buffing with Jeweler's Rouge will put a shine
back on the surface, but if buffed too much, you
will need to re-etch.
16
ContinuedWhen all etching is completed, again
wash the meteorite throughly in Dish Washing
liquid and water.Step 4 Preserving Iron
MeteoritesTwo major factors that cause a
Iron/Nickel Meteorite to rust are Chlorides, both
natural occurring and what is added during the
etching process and Water (Moisture). The more of
either, the more the meteorite will rust.If you
used Ferric Chloride as an etching material, you
have added a considerable amount of chlorides to
the surface and into surface cracks that will
result in rust if not removed.We must also
remove the water we washed the meteorite in
during the etching process.
17
ContinuedRemoving ChloridesMix a solution of
Sodium Hydroxide and Ethanol. Use about one Table
Spoon of Sodium Hydroxide to a pint of 96
Ethanol.Submerge the Meteorite in the solution
and let it soak for 5 - 10 days in the alcohol /
sodium hydroxide bath. The sodium hydroxide will
attack the Chlorides in the specimen through a
chemical reaction that combines sodium in the
solution with the chlorides on the meteorite
surface and in minute cracks and becomes common
salt (Sodium Chloride). Wash the meteorite
throughly with Dish Washing Liquid / Water.
18
Removing WaterNext, soak the Meteorite in pure
96 Ethanol for 24 hours. Place the meteorite
in you kitchen oven at the ovens lowest
temperature setting for two hours.This
completes the drying process.Final
TreatmentThe final treatment to the meteorite
is to apply a coating of oil to all surfaces of
the specimen. I use WD-40, but any light oil will
work I do not recommend using a coating such
as varnish, polyurethane, etc, because over time
most coatings will turn yellow and if you ever
need to re-etch the meteorite, you would need to
first remove the coating.
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