Thin Section Preparation At Home

Discussion:

(too old to reply)

Too_Many_Tools

2006-10-02 22:45:50 UTC

Does anyone have any suggestions, picture of amateur setups, websites
or references for preparing thin sections minerals, rocks and metals at
home?

Any homemade equipment suggestions for saws, laps, grinders and
consumables?

Thanks

TMT

Greg

2006-10-02 23:59:53 UTC

Permalink

Hello Tools, I have made thin sections of rocks on a variety of
equipment, from fancy to simple. If you are patient, you can make them
with nothing but a diamond blade wet saw as used for cutting tile, a
piece of plate glass about a foot square, and fine, medium, and coarse
carbide grit (about 100 grit to 600 grit). You can use store-bought
epoxy, but get some 2" long glass slides and the grit from a geology or
lapidary materials supplier (find them by Google).

You also need to cut a retangular block of hard smooth wood a little
larger than the slide. With a sharp chisel and router, cut out a flat
recess on one side of the block that one slide will fit snugly and
flush with the block surface, and use it to hold the slide+rock chip
while you trim it on the saw. Cut a "billet" or chip a little smaller
than a slide, grind one side smooth on the glass plate in a slurry of
grit + water, wash it, and let it get very dry (a hot plate or coffee
mug warmer is nice). Then epoxy that flat smooth chip side to a glass
slide (take care to keep out bubbles -- warming the epoxy gently first
makes it clearer). After it cures, put it in your block and trim it
carefully on the saw, cutting as close as you can to leave only a thin
slice of rock. Then grind it down on your glass plate by hand, going
from coarse to medium to fine grit. Hold it down with a few fingers
flat on the slide's back, use a figure 8 pattern, and cover all of the
glass plate so it wears evenly (it needs to stay flat). As the chip
gets close to 30 microns thick (0.03 mm) the rock will become
transluscent -- check it frequently until you get it to the proper
thickness. You can tell that by the birefringent colors of comon
minerals like feldspar and quartz (you might need a reference book with
color photos if you are not familiar with how those minerals look).

Practice is necessary! Good luck, Greg

Post by Too_Many_Tools
Does anyone have any suggestions, picture of amateur setups, websites
or references for preparing thin sections minerals, rocks and metals at
home?
Any homemade equipment suggestions for saws, laps, grinders and
consumables?
Thanks
TMT

jgandalf

2006-10-03 16:14:14 UTC

Permalink

I have a copy of a monograph published several years ago by the PMS
(Postal Microscopical Society of Great Britain) about DIY thin
sections. I also have been collecting various older books on optical
minerology, as well as 'net resources about this topic. (I'll be glad
to share.) Although it's probably cheaper to buy premade thin sections
(at about $15 each), I want to be able to say I've done it myself.
Also, I plan on preparing a representative sample of them from the
rocks on my property (I live in an interesting area of the Southern
Appalachians, where several different thrust sheets come to the
surface).

Although clear epoxies may work, it is preferable to match the RI of
the slide. A good adhesive for this is Lakeside 70C. It's a thermoset,
so you can heat it up and reposition the chip (before it gets too thin,
anyway). One technique calls for transferring the chip to a new slide
after lapping one side, in order to finish the other. I've been meaning
to order some, but they have a minimum order, which is more than I ever
would use. If you're interested, perhaps we could split the order.

Since you are one of the *very* few people I've discovered who has an
amateur interest in thin sections, feel free to email me off list at
jgandalf1 AT gmail DOT com. Be patient: I don't always check my gmail
account (attack of slack).

Regards,
Joe

Richard Owlett

2006-10-03 18:43:10 UTC

Permalink

[snip]
Since you are one of the *very* few people I've discovered who has an
amateur interest in thin sections, feel free to email me off list at
jgandalf1 AT gmail DOT com. Be patient: I don't always check my gmail
account (attack of slack).
Regards,
Joe

My I encourage you to share on sci.techniques.microscopy .

I do not own a microscope.
I'm interested in *TOO* many things to lay out the cash for everything.

I have to participate vicariously.
As I approach retirement I see my self doing more tutoring/mentoring.

I'd like to now what's feasible so I could encourage underachieving
youth with a science bent that is not quite mine.

PS. My father operated a *LEGAL* land based spark gap transmitter and
made capacitors he described as X micro farads per gallon ;)

Too_Many_Tools

2006-10-04 17:13:27 UTC

Permalink

Jeff,

How do you make your thin sections?

TMT

Post by jgandalf

I have a copy of a monograph published several years ago by the PMS
(Postal Microscopical Society of Great Britain) about DIY thin
sections. I also have been collecting various older books on optical
minerology, as well as 'net resources about this topic. (I'll be glad
to share.) Although it's probably cheaper to buy premade thin sections
(at about $15 each), I want to be able to say I've done it myself.
Also, I plan on preparing a representative sample of them from the
rocks on my property (I live in an interesting area of the Southern
Appalachians, where several different thrust sheets come to the
surface).
Although clear epoxies may work, it is preferable to match the RI of
the slide. A good adhesive for this is Lakeside 70C. It's a thermoset,
so you can heat it up and reposition the chip (before it gets too thin,
anyway). One technique calls for transferring the chip to a new slide
after lapping one side, in order to finish the other. I've been meaning
to order some, but they have a minimum order, which is more than I ever
would use. If you're interested, perhaps we could split the order.
Since you are one of the *very* few people I've discovered who has an
amateur interest in thin sections, feel free to email me off list at
jgandalf1 AT gmail DOT com. Be patient: I don't always check my gmail
account (attack of slack).
Regards,
Joe

Greg

2006-10-03 23:05:11 UTC

Permalink

I neglected to recommend Hillquist for thin-section making supplies
(http://www.hillquist.com/index.htm). Hillquist makes excellent
machines as well, but they are not cheap! Even when used t-section
machines come up on eBay (very rarely), they can run into several
thousand dollars. But with a machine, you can make a bunch per hour by
hand, vs 1 slide or fewer per hour by my method already described.
Hillquist epoxy is first rate and comes in bottles large enough to make
many hundreds of sections, perhaps more than you need. Most epoxies are
close enough to glass slides in refractive index to work OK. Some
people "frost" one side of the slide on the glass (or rotary) lap to
increase the sticking power of the rock chip to the slide, but it is
not really necessary with epoxy (although it can be helpful for some
other adhesives). Good luck!

mike.james

2006-10-04 07:54:13 UTC

Permalink

As well as being interested in geology (amateur) I also stick my nose into
astronomy and am fascinated by the difference between the two from the
commercial point of view.

Amateur geology has on offer perhaps a hand lens, maps, books and perhaps
for the really serious a hammer. Total cost not much over the lifetime of
the interest.

Amateur astronomy has by comparison lots of stuff to buy. Telescopes start
at a few hundreds (dollars or pounds) but go up to thousands. You can buy
cameras, processing software, even complete observatories with domes. The
resulting commerce allows lots of magazines to exist on the advertising and
the whole area is - for want of a better word "dynamic" and booming. They,
amateur astronomers that is,

also seem to be taken reasonably seriously and do make contributions to the
subject.

Is this because geology has no tools that the amateur could buy? Well
possibly

but why no reasonably priced kit for making thin sections and looking at
them?

No demand I guess or is it that no one in their right mind would take up
amateur geology because there are no real facilities and no "toys" to be
had?

There is currently something that makes spending vast fortunes on home
astronomy

acceptable but if you were to propose the same for home geology I think you'd
be

regarded as a nut.

What about professional geologists (probably university based) doing
something to

get amateurs involved - and I don't mean a rock fair or a hands on minerals
day.

I mean get them out to do some of your field work.

It should be easy to organise - all it needs is a web site.

Comments?

mikej

Carl 1 Lucky Texan

2006-10-04 11:23:37 UTC

Permalink

Post by mike.james

As well as being interested in geology (amateur) I also stick my nose into
astronomy and am fascinated by the difference between the two from the
commercial point of view.
Amateur geology has on offer perhaps a hand lens, maps, books and perhaps
for the really serious a hammer. Total cost not much over the lifetime of
the interest.
Amateur astronomy has by comparison lots of stuff to buy. Telescopes start
at a few hundreds (dollars or pounds) but go up to thousands. You can buy
cameras, processing software, even complete observatories with domes. The
resulting commerce allows lots of magazines to exist on the advertising and
the whole area is - for want of a better word "dynamic" and booming. They,
amateur astronomers that is,
also seem to be taken reasonably seriously and do make contributions to the
subject.
Is this because geology has no tools that the amateur could buy? Well
possibly
but why no reasonably priced kit for making thin sections and looking at
them?
No demand I guess or is it that no one in their right mind would take up
amateur geology because there are no real facilities and no "toys" to be
had?
There is currently something that makes spending vast fortunes on home
astronomy
acceptable but if you were to propose the same for home geology I think you'd
be
regarded as a nut.
What about professional geologists (probably university based) doing
something to
get amateurs involved - and I don't mean a rock fair or a hands on minerals
day.
I mean get them out to do some of your field work.
It should be easy to organise - all it needs is a web site.
Comments?
mikej

Most larger cities have a Gem & Mineral Society. many of them seem to
focus on jewelry but others are very active with field trips for
collecting and speakers/semonars on various subjects. My club has stuff
donated to it occasionally and last night at our annual fundreaising
auction a Buehler saw for sectioning specimens sold for $55. It needed a
blade and some work - but it looked mostly complete. Donated to us by Mobil.
A tile saw with the correct blade and a flat lap MAY be all you would
need for prepping thin sections - I dunno. The Microsope is gonna set
you back some I guess. Still, probably also use it for gemology if you
wanted.
check at www.amfed.org for a club near you. Even if they aren't now
pursueing geological study, you might be an instructor for the club in
that discipline!

Carl

--
to reply, change ( .not) to ( .net)

Too_Many_Tools

2006-10-04 16:59:58 UTC

Permalink

I think the real tough workaround is the grinding/lapping cycle.

You can find used saws or make a saw but you are hard pressed for
finding a good grinding setup that allows the accuracy needed to make
thin sections. This one of the reason why I am asking about homemade
setups. If anyone has links or pictures to any solutions, I would like
to hear about them.

TMT

Post by Carl 1 Lucky Texan

Post by mike.james

As well as being interested in geology (amateur) I also stick my nose into
astronomy and am fascinated by the difference between the two from the
commercial point of view.
Amateur geology has on offer perhaps a hand lens, maps, books and perhaps
for the really serious a hammer. Total cost not much over the lifetime of
the interest.
Amateur astronomy has by comparison lots of stuff to buy. Telescopes start
at a few hundreds (dollars or pounds) but go up to thousands. You can buy
cameras, processing software, even complete observatories with domes. The
resulting commerce allows lots of magazines to exist on the advertising and
the whole area is - for want of a better word "dynamic" and booming. They,
amateur astronomers that is,
also seem to be taken reasonably seriously and do make contributions to the
subject.
Is this because geology has no tools that the amateur could buy? Well
possibly
but why no reasonably priced kit for making thin sections and looking at
them?
No demand I guess or is it that no one in their right mind would take up
amateur geology because there are no real facilities and no "toys" to be
had?
There is currently something that makes spending vast fortunes on home
astronomy
acceptable but if you were to propose the same for home geology I think you'd
be
regarded as a nut.
What about professional geologists (probably university based) doing
something to
get amateurs involved - and I don't mean a rock fair or a hands on minerals
day.
I mean get them out to do some of your field work.
It should be easy to organise - all it needs is a web site.
Comments?
mikej

Gregg

2006-10-05 09:56:46 UTC

Permalink

Post by Too_Many_Tools
I think the real tough workaround is the grinding/lapping cycle.
You can find used saws or make a saw but you are hard pressed for
finding a good grinding setup that allows the accuracy needed to make
thin sections. This one of the reason why I am asking about homemade
setups. If anyone has links or pictures to any solutions, I would like
to hear about them.
TMT

<snip>

Did you look at equipment for sharping wood working tools?
Chisels, planes blades etc...
I've seen horizontal disc setups that look very much like a lapping wheel.

Just a thought

Gregg

Too_Many_Tools

2006-10-05 15:20:37 UTC

Permalink

Thanks for the suggestion...

That is one of the reasons why I am asking questions about the process
of producing thin sections....it would seem that there might be a
number of common tools that could serve double duty.

For slab sawing and trimming, a cheap tile seems to get one close to
the dimensions needed. The thinner the original section, the less
grinding and lapping that has to be done.

For grinding, I have seen belt sanders used to roughly grind dimension
samples and then the wet horizontal grinders that woodworkers use so
take the samples further...both are far cheaper than the professional
machines used.

I also note the amateur telescope makers use homemade grinder machines
to work glass all the time.

One could also look at the surface grinder that metal workers use.

TMT

Post by Gregg

<snip>
Did you look at equipment for sharping wood working tools?
Chisels, planes blades etc...
I've seen horizontal disc setups that look very much like a lapping wheel.
Just a thought
Gregg

Carl 1 Lucky Texan

2006-10-05 21:29:33 UTC

Permalink

Post by Too_Many_Tools
Thanks for the suggestion...
That is one of the reasons why I am asking questions about the process
of producing thin sections....it would seem that there might be a
number of common tools that could serve double duty.
For slab sawing and trimming, a cheap tile seems to get one close to
the dimensions needed. The thinner the original section, the less
grinding and lapping that has to be done.
For grinding, I have seen belt sanders used to roughly grind dimension
samples and then the wet horizontal grinders that woodworkers use so
take the samples further...both are far cheaper than the professional
machines used.
I also note the amateur telescope makers use homemade grinder machines
to work glass all the time.
One could also look at the surface grinder that metal workers use.
TMT

Post by Gregg

<snip>
Did you look at equipment for sharping wood working tools?
Chisels, planes blades etc...
I've seen horizontal disc setups that look very much like a lapping wheel.
Just a thought
Gregg

http://tomaszewski.net/Kreigh/Minerals/Homemade.shtml

http://www.djwd.net/members/ghrs/tools_and_supplies.html

http://tinyurl.com/fd9tt

Carl

--
to reply, change ( .not) to ( .net)

will1

2006-10-04 19:46:52 UTC

Permalink

Most of the lapidary equipment can be purchased used and at reasonable
prices at rock shops, rock and gem shows, and some through e- bay. just get
a used flat lap to grind the section down to approximate desired thickness.
Diamond laps are really very good for this part of the process. Finish the
section by hand using a piece of glass and fine grit as mentioned in the
other posts in this thread. If you are close to a state college or
university that has a geology department you might be able to use their
equipment or get a student to make the sections for you at a good rate. At
the least, you can see their set up for ideas. Will E. ps. don't forget to
Google 'thin section preparation.

Too_Many_Tools

2006-10-04 20:33:34 UTC

Permalink

Rotary or vibration lap?

How do you control the depth of grind and flatness?

TMT

Post by will1
Most of the lapidary equipment can be purchased used and at reasonable
prices at rock shops, rock and gem shows, and some through e- bay. just get
a used flat lap to grind the section down to approximate desired thickness.
Diamond laps are really very good for this part of the process. Finish the
section by hand using a piece of glass and fine grit as mentioned in the
other posts in this thread. If you are close to a state college or
university that has a geology department you might be able to use their
equipment or get a student to make the sections for you at a good rate. At
the least, you can see their set up for ideas. Will E. ps. don't forget to
Google 'thin section preparation.

Greg

2006-10-04 20:59:56 UTC

Permalink

Laps are not a big issue, motorized ones are common lapidary equipment,
and they make the process faster and easier than grinding a slide on a
glass plate. But not absolutely necessary for a home shop. The real
finesse is getting the rock slice very close to 30 microns. Believe
me, I have made more than 3000 rock and sediment thin sections as a
geology student and later as a faculty member, so I know the process
well. Larger geology programs might have an automated thin section
machine that can be carefully set up and calibrated to produce 10
sections as a time to the proper thickness. These cost really big
bucks, as you might expect. Otherwise, the ONLY way to get the slide to
30 microns is by hand finishing, and you need to check it over and over
again using a polarizing microscope until it is correct. Quartz and
feldspar are the best minerals for this observation, as they change
their birefringence (interference colors) as they approach 30 microns.
I have taught many students the technique. It is not a big deal, and
even enjoyable.

Too_Many_Tools

2006-10-04 23:57:26 UTC

Permalink

Thanks for the information Greg.

I appreciate the links but again I note that there is almost no
information concernng making the actual thin sections...an indication
that it is "left up to the student" to figure out.

Can anyone provide a link to a step by step discussion of making thin
sections in a amateur setting with easily gotten equipment? I have yet
to find one.

While on the subject of thin sections, what brand of microscope and
accessories would anyone suggest for this efffort? Any favorites? I
note that polarizing microscope are a rariety in the used market.

TMT

Post by Greg
Laps are not a big issue, motorized ones are common lapidary equipment,
and they make the process faster and easier than grinding a slide on a
glass plate. But not absolutely necessary for a home shop. The real
finesse is getting the rock slice very close to 30 microns. Believe
me, I have made more than 3000 rock and sediment thin sections as a
geology student and later as a faculty member, so I know the process
well. Larger geology programs might have an automated thin section
machine that can be carefully set up and calibrated to produce 10
sections as a time to the proper thickness. These cost really big
bucks, as you might expect. Otherwise, the ONLY way to get the slide to
30 microns is by hand finishing, and you need to check it over and over
again using a polarizing microscope until it is correct. Quartz and
feldspar are the best minerals for this observation, as they change
their birefringence (interference colors) as they approach 30 microns.
I have taught many students the technique. It is not a big deal, and
even enjoyable.

Greg

2006-10-05 01:00:52 UTC

Permalink

Yes, as Will says, Google 'thin section preparation.' Not much point
in making or having thin sections of rocks without a petrographic
microscope to look at them, or at least a 'simple polarizing' scope (a
biological scope with two polarizing filters). Be very careful to not
get wet grit on or in your microscope when you are checking the slide
for proper thickness.

Since you asked about polarizing scopes, you can usually find some of
my favorite brands in my Stones2Gems store on eBay (a shamless plug,
sorry), but there are also several very interesting complete pol
systems up for bid on eBay right now, an Olympus BHA-P and also a nice
looking Nikon Labophot. As you note, such offerings are rare. I have an
article on my favorite benchtop pol scopes coming out later this month
in Micscape Magazine. I am thinking I should write up a step-by-step
using a home-based thin section procedure with the simple tools we have
mentioned already, with photos. Maybe another Micscape article?
regards from Greg

Post by Too_Many_Tools
Thanks for the information Greg.
I appreciate the links but again I note that there is almost no
information concernng making the actual thin sections...an indication
that it is "left up to the student" to figure out.
Can anyone provide a link to a step by step discussion of making thin
sections in a amateur setting with easily gotten equipment? I have yet
to find one.
While on the subject of thin sections, what brand of microscope and
accessories would anyone suggest for this efffort? Any favorites? I
note that polarizing microscope are a rariety in the used market.
TMT

Too_Many_Tools

2006-10-05 02:03:32 UTC

Permalink

" I am thinking I should write up a step-by-step
using a home-based thin section procedure with the simple tools we have

mentioned already, with photos. Maybe another Micscape article? "

EXCELLENT idea....considering I have yet to find anything similar on
the Web, it will be well received.

I do have access to several polarizing scopes but am considering
acquiring several more for others to use. Are there any older brands to
consider...AO,Nikon,Olympus,Vickers...and if so which one and what
accessories are commonly used? Considering that they rarely surface and
the accessories are expensive, the more information one has the more
intelligent the selection process.

TMT

Post by Greg
Yes, as Will says, Google 'thin section preparation.' Not much point
in making or having thin sections of rocks without a petrographic
microscope to look at them, or at least a 'simple polarizing' scope (a
biological scope with two polarizing filters). Be very careful to not
get wet grit on or in your microscope when you are checking the slide
for proper thickness.
Since you asked about polarizing scopes, you can usually find some of
my favorite brands in my Stones2Gems store on eBay (a shamless plug,
sorry), but there are also several very interesting complete pol
systems up for bid on eBay right now, an Olympus BHA-P and also a nice
looking Nikon Labophot. As you note, such offerings are rare. I have an
article on my favorite benchtop pol scopes coming out later this month
in Micscape Magazine. I am thinking I should write up a step-by-step
using a home-based thin section procedure with the simple tools we have
mentioned already, with photos. Maybe another Micscape article?
regards from Greg

Greg

2006-10-05 10:25:43 UTC

Permalink

In the 1960s and 70s, a lot of colleges used monocular Vickers and
Zeiss Standards (if they could afford them) for student lab teaching.
These are probably the most commonly seen lab scopes on eBay, and are
often affordable. The Zeiss is a little better but more expensive. I
have both in my Stones2Gems store, and both are also on eBay by others
at this time. Be warned, some of them have had a hard life! If you
have the scratch, the best bench top pol scope is the Olympus BH-2 BHTP
or BHSP, of the older 160 mm tube length. The AO 110 pol scope is an
excellent machine for the low prices I have seen. You need objectives
of low power (2.5 ot 4x), also 10x and 40x. Others are just gravy.
Also a Bertrand lens, and a whole-wave compensating plate (the same one
might fit different brands). If you consider a Zeiss, check first about
the condition of its analyzer filter, which might be partially
delaminated (I have seen many like that).

Post by Too_Many_Tools
" I am thinking I should write up a step-by-step
using a home-based thin section procedure with the simple tools we have
mentioned already, with photos. Maybe another Micscape article? "
EXCELLENT idea....considering I have yet to find anything similar on
the Web, it will be well received.
I do have access to several polarizing scopes but am considering
acquiring several more for others to use. Are there any older brands to
consider...AO,Nikon,Olympus,Vickers...and if so which one and what
accessories are commonly used? Considering that they rarely surface and
the accessories are expensive, the more information one has the more
intelligent the selection process.
TMT

Too_Many_Tools

2006-10-26 16:39:54 UTC

Permalink

Greg,

Good article....more to come?

http://www.microscopy-uk.org.uk/

TMT

will1

2006-10-05 00:35:50 UTC

Permalink

Make a wedge out of quartz and placed it between two pieces of polarizing
filters. Polaroid sun glasses or

photography filters would work. The polaroids are rotated until light
passing through them are blocked, a

condition called 'crossed polaroids'. You will see several bands of color
near the thin edge of the wedge. the first

yellow band is in the area where the wedge is .03mm in thickness. The game
is to get as close as you can to

this thickness, about .1mm, with trim saws and laps. THEN you add a little
fine grit and water to a flat surface

such as a piece of glass and start rubbing the thin section on this treated
surface, usually in a figure 8 pattern,

to get to .03 mm. You do this by rubbing a little and placing the thin
section between the polaroids, rub and

check, rub and check, until you see the colors created by various minerals.
If there is quartz ,yellow is the place to

stop. If you have feldspar then white or gray is good. Other minerals will
show different colors and you need to

look at a chart found in any good optical mineralogy text to understand what
thickness and minerals you have. If

you can get a few sample thin sections to use as a reference that would be
great. Again, Google 'thin section

preparation'. Lots of hits.

By the way, what kinds of samples are you working with? Will E.

Post by Too_Many_Tools
Rotary or vibration lap?
How do you control the depth of grind and flatness?
TMT

Too_Many_Tools

2006-10-05 00:56:44 UTC

Permalink

Thanks for the information....

I have been using Google as one of my research tools.

I am asking for advice because I will likely be building some machines
to hopefully automate some of this "try it till it is right" final
staging for the thin sections.

Since it is not just one thickness of a certain width, one needs to
understand the problem before construction.

I should also mention that I will be doing natural metal bearing ores
some of which will be opaque so advice concerning metallurgical samples
would be appreciated also.

Any more information anyone?

TMT

Post by will1
Make a wedge out of quartz and placed it between two pieces of polarizing
filters. Polaroid sun glasses or
photography filters would work. The polaroids are rotated until light
passing through them are blocked, a
condition called 'crossed polaroids'. You will see several bands of color
near the thin edge of the wedge. the first
yellow band is in the area where the wedge is .03mm in thickness. The game
is to get as close as you can to
this thickness, about .1mm, with trim saws and laps. THEN you add a little
fine grit and water to a flat surface
such as a piece of glass and start rubbing the thin section on this treated
surface, usually in a figure 8 pattern,
to get to .03 mm. You do this by rubbing a little and placing the thin
section between the polaroids, rub and
check, rub and check, until you see the colors created by various minerals.
If there is quartz ,yellow is the place to
stop. If you have feldspar then white or gray is good. Other minerals will
show different colors and you need to
look at a chart found in any good optical mineralogy text to understand what
thickness and minerals you have. If
you can get a few sample thin sections to use as a reference that would be
great. Again, Google 'thin section
preparation'. Lots of hits.
By the way, what kinds of samples are you working with? Will E.

Post by Too_Many_Tools
Rotary or vibration lap?
How do you control the depth of grind and flatness?
TMT

will1

2006-10-05 03:34:12 UTC

Permalink

Post by Too_Many_Tools
I will likely be building some machines
to hopefully automate some of this "try it till it is right" final
staging for the thin sections.

The final touch in making thin sections is more of an art form than a
mechanical process. But those folks that make Si wafers have it down.

Just a note, My old petrology prof once told the class,

"A microscope does not solve problems, it just magnifies them." Will E.

Clyde Spencer

2006-10-05 23:16:10 UTC

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Making pucks to hold polished ore minerals is less challenging than making a
thin-section. Find a plastic ring about 2" in diameter (not critical as
long as it is large enough not to fall into the hole usually in the center
of a rotating stage). Coat the bottom and inside of the ring with Vaseline
to seal it and place it on some waxpaper or plastic film. Place the mineral
sample in the center of the ring. The flatter the surface that is face
down, the less work you will have to do. Fill the ring with epoxy or
acrylic casting resin. After it has cured, pop out the casting. Then get
several sheets of wet-dry emery paper at your hardware store and wet lap by
hand with the emery paper on a flat piece of glass. Start with coarse at
about 80 or 100 grit and progress up to at least 600 grit, washing and
checking along the way to be sure you have removed the scratches from the
previous step. At this point I go to diamond paste of about 6 micron, 3
micron, 1 micron, and finally 0.5 micron on fabric or Lucite. The trick is
to end up with a high polish without any visible scratches. Using a
polishing buffer is alright for some minerals, but may cause plucking on
soft, easily cleaveable minerals like galena. I just do hand polishing with
the diamond paste to avoid the plucking and heat generated by a buffer. The
last thing is that you either have to mount the puck on a piece of
plasticine or modeling clay to be sure the surface is at right angles to the
optic axis of your vertically illuminated microscope. I usually turn the
puck base on my small lathe to be sure that it is parallel to the polished
face. Oh yes, if you want to examine opaque ore minerals, you will have to
get an ore microscope with a vertical illuminator. They are even rarer than
the petrographic microscopes, but they are usually cheaper.
Clyde Spencer

Post by Too_Many_Tools
Thanks for the information....
I have been using Google as one of my research tools.
I am asking for advice because I will likely be building some machines
to hopefully automate some of this "try it till it is right" final
staging for the thin sections.
Since it is not just one thickness of a certain width, one needs to
understand the problem before construction.
I should also mention that I will be doing natural metal bearing ores
some of which will be opaque so advice concerning metallurgical samples
would be appreciated also.
Any more information anyone?
TMT

Post by Too_Many_Tools
Rotary or vibration lap?
How do you control the depth of grind and flatness?
TMT

Post by will1
Most of the lapidary equipment can be purchased used and at reasonable
prices at rock shops, rock and gem shows, and some through e- bay.

just