# Petoskey Stone - this one almost beat me



## Sylvanite (Oct 4, 2010)

I've been wanting to make this pen for quite a while now.  I finally got a free day to try, and I nearly didn't make it.  The stuff kept shattering on me.  They say that the true value of something is the effort it took to get - if so, this is one of my more expensive pens.  I've earmarked it as a christmas gift for a sister (don't tell her though).

Can anybody guess what the material is?


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## ThomJ (Oct 4, 2010)

Nice pen............Alabaster?


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## ericw95 (Oct 4, 2010)

loofa sponge?


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## Buzzzz4 (Oct 4, 2010)

Looks like some type of shell. Great look!


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## Ligget (Oct 4, 2010)

Beautiful pen, not sure what the material is but it looks great!


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## srf1114 (Oct 4, 2010)

looks like Petosky Stone.


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## jaywood1207 (Oct 4, 2010)

Nice job on the fit and finish.  Bone of some sort??


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## Monty (Oct 4, 2010)

Is it limestone?


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## boxerman (Oct 4, 2010)

Very nice pen.


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## seamus7227 (Oct 4, 2010)

Caliche?


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## Skye (Oct 4, 2010)

I'll guess some sort of bone.


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## Parson (Oct 4, 2010)

fossil stone?


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## jskeen (Oct 4, 2010)

I'm thinking some sort of fossil bearing limestone.  Can't place the particular type though.  Pretty stuff, whatever it is.


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## workinforwood (Oct 5, 2010)

Pen looks beautiful whatever it is.


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## Mack C. (Oct 5, 2010)

It looks like Corian® to me!


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## Steve Busey (Oct 5, 2010)

Perhaps some old coral...


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## aggromere (Oct 5, 2010)

I have no idea what the material is, but the pen is beautiful.


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## Nikitas (Oct 5, 2010)

Nice looking pen, and no idea on the material...


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## snyiper (Oct 5, 2010)

Im with Mack it looks like Corian to me as well.


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## Sylvanite (Oct 5, 2010)

*Good guesses!*

Great guesses all around.  I thought it would be more of a challenge, and planned to give a few hints.  Several people, however, were remarkably close, and one nailed it right off the bat.

Leave it to a Michigander to recognize:





srf1114 said:


> Petosky Stone.



Yep, it's Petoskey Stone.  Growing up in Michigan, we used to shape petoskey stones by rubbing them on the driveway, so I knew that the stone was soft enough.  What I didn't know, however, was how brittle it would be.  I've never seen (or heard of) a petoskey stone pen before - and maybe now I understand why.

This one didn't come out with the typical hexagonal pattern, but the fossils are still distinctly visible.

Regards,
Eric


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## jskeen (Oct 5, 2010)

I thought about that, but decided, Nah, North Carolina is way too far away from the lower peninsula for it to be a real petoskey stone.  Gotta be some other kind of fossil bearing limestone.  Never know where yankee's are going to transplant themselves nowdays.


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## Chasper (Oct 5, 2010)

Outstanding turning work.  I haven't tried petosky stone, but I've tried several other fossilliferos limestones and other types of coral head fossils, without real success on any of them.  Drilling the holes has always been the toughest part for me.  Good work on getting it turned, I know how chip-prone it is.  

Did you use standard lathe tools or a grinder on the lathe.  This is what they make lapidary lathes for.


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## maxwell_smart007 (Oct 5, 2010)

I figured the guesses would be easy - it's right in the thread title!


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## Parson (Oct 5, 2010)

I think he just changed the title


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## bitshird (Oct 5, 2010)

Eric, I've cut Cabochons from that stuff, I couldn't imagine making a pen from it though, it's actually a fossilized Coral found up on the great lakes only in one spot if I remember correctly, Excellent creation, I hope she realizes what you went through to make it, it's a neat pen.


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## Sylvanite (Oct 5, 2010)

bitshird said:


> ... it's actually a fossilized Coral found up on the great lakes only in one spot if I remember correctly


Yes, Petoskey Stone is fossilized coral that grew around 350 million years ago.  Pieces of the stone were broken off by glaciers and deposited on the northern shore of Michigan's Lower Peninsula.  It is pretty much unique to that area, and is the state stone of Michigan.



Chasper said:


> I haven't tried petosky stone, but I've tried several other fossilliferos limestones and other types of coral head fossils, without real success on any of them.  Drilling the holes has always been the toughest part ... I know how chip-prone it is.
> 
> Did you use standard lathe tools or a grinder on the lathe.  This is what they make lapidary lathes for.


I expect that petoskey stone is similar to other limestone fossils and has similar turning properties.  Working it presented several difficulties.

Uneven density.  Petoskey stone is generally pretty soft, but can have hard spots or hard mud inclusions.  In my first attempts, I mounted a piece in a chuck and rounded it down with a file.  That didn't work.  The soft spots wore down and hard spots didn't.  The blank quickly got out-of-round.  I eventually took to rounding the blank as much as possible with a bench grinder, and then turning it on a metal lathe with carbide cutters.  That way, I could keep it cylindrical, and take off only 0.005" at a time.  That helped reduce the fractures.  Fortunately, most of these breaks were clean and could be glued back together.
Brittleness.  Catches easily break the stone, especially when drilling.  I tried regular drill bits and brad-point bits.  Both shattered the blank beyond repair.  It broke into too many pieces and too much dust to glue.  I wound up drilling from both ends (on the lathe) with a masonry bit.  I kept the rounded blank as large as possible (nearly an inch in diameter) mounted in an er40 chuck for maximum support.  The masonry bit didn't break the stone.  Unfortunately, I don't have (and can't find) one of the right size, so I used the closest fitting masonry bit, and reamed out the hole with the correct HSS bit.  I had a few breaks at that point, but they were recoverable.
Chipping.  After drilling, I glued in a tube, sanded the ends flush, mouned it on a mandrel with bushings, and turned it down.  As I said earlier, I turned it on a metal lathe and took very light passes.  The blank held together, but still suffered lots of tear-out.  I stopped using cutters when the blank was about 0.030" proud, and sanded it the rest of the way.  Nevertheless, there were some voids that I had to fill with rock dust and CA glue.
Oh, and now I have lime dust all over my shop too.  That's tough on the tools (I'll have to thoroughly clean and relubricate the lathe), and on the eyes (lime burns).

But, I like the pen, and your kind comments.

Regards,
Eric


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## Snorton20 (Oct 5, 2010)

What a beautiful pen, great job.   What pen kit is that? and where did you get it from?


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## CSue (Oct 6, 2010)

That is a magnificient pen!  Wonderful work!  She's going to love it!


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## Sylvanite (Oct 6, 2010)

Snorton20 said:


> What pen kit is that? and where did you get it from?


The kit is an Elegant Beauty by Dayacom - not to be confused with the Elegant Beauty by Berea.  The Dayacom version uses a smaller diameter tube, so the blank doesn't have to be turned as thin.  I like this kit when I need thicker material - such as my coachwhipped pens.  I didn't want to have to turn the petoskey stone very thin either, for fear it would be too fragile.

This kit also produces a smaller, more feminine looking pen (although I've carried one myself).  An interesting feature is that the transmission is above the clip.  The finial turns to extend the refill.

If memory serves, I stocked up when Anthony Turchetta offered them - but I don't see the kits on his website anymore.  You can order them from http://www.laulauwood.net.

Regards,
Eric


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