What to use to cut Petrified Wood?

[FossilsandScience]

Hey everyone,

 

I have a ton of petrified wood that I would like to cut and polish, but I don’t know the proper tools to use. The largest piece is about 4” in width. Any ideas?

 

Thanks!

[snolly50]

Look into joining your local gem/rock club. Sometimes such an organization will have a "workshop" with the very power equipment you will need; that is shared by members.

[Norki]

You'll need a pretty serious diamond grinding wheel to do anything with petrified wood, it's usually composed of nearly pure silica.

[Wrangellian]

What snolly said. Silica/quartz is one of the best materials for lapidary equipment. If a rock is too soft, it's not generally good for lapidary!

There are mechanized saws (as opposed to hand-held) that will make a nice clean cut (or series of parallel cuts for slabbing), and then the flat lap for polishing the sliced surface.

 

[digit]

Ditto what the others have said above--lapidary tools can make some beautiful pieces. Seek out a local lapidary club to get involved in this tangentially related hobby.

 

If you have lots of smaller chunks, you might also consider getting a rock tumbler. I have various pretty rocks (including some chunks of petrified wood) currently tumbling in my garage. I have a larger capacity (15 pound) tumbler from a company called Thumler's Tumblers (easily found on the inter-webber-net).

 

 

Cheers.

 

-Ken

[Bob Saunders]

Where I live the gem and minerals clubs do not own rock saws, but a few members may cut a piece. Best rock saw would be a 14-22 inch saw with auto feed and a mineral oil cooling bath. Read-large foot print and expensive, often requires 220 volt power. also do you plan to polish one end for display? Some use a flat lap machine. 

[Sagebrush Steve]

Depends on exactly what you want to do.  If you just want to cut the end flat and polish it, the rock cutting saws mentioned above will work.  But if your largest piece is only 4 inches across and most are smaller, you don’t need a really large saw.  My family used to own a lapidary store and we had 14” and 22” power-feed diamond saws with recirculating oil coolant.  We also had a 6” trim saw with water coolant that didn’t have an automated feed, you fed the material in by hand.  That was the one I used the most. Nowadays I don’t have any of those but I do have a tile saw with a diamond blade I picked up from Harbor Freight for under $100.  I’ve found it works well as long as you feed the material in slowly and don’t force it.

 

Polishing is another story.  A flat lap can do the job if the length of the piece is fairly short.  Here is one from Lortone: https://lortone.com/collections/oscillating-laps?info&page=1.  Longer pieces could fall over while being polished in the lap.  For those, you would be better off with a polishing machine from a place like CabKing: https://cabking.com/collections/cabking-machines/products/cabking-6.  That is also what you will need if you want to do anything more elaborate like make polished cabochons for use in jewelry.  As others have said, this is not the kind of thing you want to learn on your own, try to find a lapidary club.  Some junior colleges also have classes on polishing stones for jewelry.

 

I will also say that the quality of the polish will depend a lot on the quality of the petrified wood.  Material that is high in silica should take a good polish.  I’ve seen a lot of material that is quite porous when you cut it.  That kind wont polish very well.

 

[Mark Kmiecik]

Most rock/fossil clubs will have a bunch of folks who are into lapidary arts and will help and advise. Most clubs are dirt cheap to join and offer many areas of "earth sciences" for the money. Best investment you can find.