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GneissWare
Joined: 07 Mar 2008
Posts: 1287
Location: California
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Posted: Jun 28, 2015 18:00 Post subject: Removing matrix using tile saw and air scribe |
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On another site, people have asked how to reduce the thickness of a specimen without just sawing it flat and leaving hideous saw marks. This is the technique I use to create more natural surfaces, and still remove lots of matrix. It may interest some people here as well.
Note that this is not the final specimen, as it needs more work to expose the garnets better. I usually make a few passes, each removing less material, as I get closer to the crystals I want to preserve. I will post the final specimen at some point, when I finish it.
I did this prep work in about 12 minutes total, from pulling out the saw to the final photo.
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Before and after photo, showing the rock with cuts made to reduce thickness, and the final results. |
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Starting to make the kerf cuts. |
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Same kerf cuts from back of specimen. |
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Specimen before any scribing work started. Using a ME9100 scribe from Paleo Tools in Utah. |
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Using the scribe, the kerfs are starting to be removed, simply by gently touching tip of scribe to the flat sawn piece. |
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All the kerfs are now removed, leaving saw marks which will be cleaned up using the scribe to remove excess material. |
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Many of the saw marks are now removed. If you look carefully, you can still see a few. |
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Top of the specimen with saw marks removed. You can still see a few scribe marks, which air abrasion will fix. This is good enough for the base of a specimen, if you don't like sawn bases. |
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Pierre Joubert
Joined: 09 Mar 2012
Posts: 1605
Location: Western Cape
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Posted: Jun 29, 2015 09:16 Post subject: Re: Removing matrix using tile saw and air scribe |
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Hi Bob, thank you for sharing this technique. I have used this method often on wood but not rock. The matrix in the pictures looks soft. Will it work as well with something like basalt?
_________________ Pierre Joubert
'The tree of silence bears the fruit of peace. ' |
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GneissWare
Joined: 07 Mar 2008
Posts: 1287
Location: California
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Posted: Jun 29, 2015 09:36 Post subject: Re: Removing matrix using tile saw and air scribe |
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Hi Pierre,
This is a pretty tough matrix -- tactite from a skarn.
I have used this method on everything, with the hardest being a silicified quartzite-conglomerate, which was very hard and very dense. It takes longer to remove the saw marks with the scribe with really hard material. But, if the material is homogeneous, like quartz, the scribe will often cause the material to shatter leaving a nice natural surface with little effort.
I would expect the sawing of basalt would take longer than the time to scribe the saw marks off. With really tough material, you can also use a screwdriver to knock off the kerfs prior to scribing.
Like most prep techniques, it will be different depending on the material you are processing.
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vicen
Joined: 25 Aug 2011
Posts: 20
Location: Edinburgh
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Posted: Jun 30, 2015 03:39 Post subject: Re: Removing matrix using tile saw and air scribe |
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Hi.
I use this technique too to help minimising the matrix in our collections.
I would like to point out that it cannot be used in material sensitive to water, as the saw need water/fluid to operate.
Check the material carefully before using the saw as the vibration produced by the saw can break the minerals if there is any small fissure.
_________________ Geological Conservator/Preparator
Natural Sciences Department
National Museums Scotland
242 West Granton Road
Edinburgh EH5 1JA |
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GneissWare
Joined: 07 Mar 2008
Posts: 1287
Location: California
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Posted: Jun 30, 2015 09:24 Post subject: Re: Removing matrix using tile saw and air scribe |
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Thought it might be interesting to see how this piece evolves...
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Two more passes using the saw to reduce the matrix thickness, and using the scribe to reveal more of the garnets. About 30 minutes total time in prepping this specimen. |
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Pierre Joubert
Joined: 09 Mar 2012
Posts: 1605
Location: Western Cape
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Posted: Jul 01, 2015 01:19 Post subject: Re: Removing matrix using tile saw and air scribe |
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Hi Bob, I am unfamiliar with air scribes and visited internet to see how they work. They are very nifty tools! Thank you for this valuable contribution.
_________________ Pierre Joubert
'The tree of silence bears the fruit of peace. ' |
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GneissWare
Joined: 07 Mar 2008
Posts: 1287
Location: California
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Posted: Jul 01, 2015 09:39 Post subject: Re: Removing matrix using tile saw and air scribe |
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Here is the final specimen after scribing. It still needs some micro abrasion work to remove matrix on the garnet faces that will not easily (or safely) come of with the air scribe.
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About 3 more times using the saw to remove matrix, and then carefully working on removal of matrix around the garnets using the scribe. |
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Specimen at beginning of process and after matrix removal. There is about an hour total time in this specimen.
Collectors no longer seem to want representative specimens (like the original). As can be seen with this simple example, to provide specimens that collectors want takes quite an amount of time and equipment to prepare specimens, so it is not surprising that prices are higher now than they were a decade ago. Unless you actually field collected a specimen, the chances are that work like this has been done on your specimens. |
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GneissWare
Joined: 07 Mar 2008
Posts: 1287
Location: California
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Posted: Jul 14, 2015 12:22 Post subject: Removing matrix using tile saw and air scribe |
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Thought I would post another example showing how to reduce matrix, and also some before and after photos following air abrasion. This is an old specimen of Benitoite and Neptunite that I was asked to trim and clean. It was not well prepared previously, so too much natrolite was removed, and the acid used was to strong, leaving a hackly texture on the natrolite. It was also too thick and heavy.
Mineral: | Benitoite and Neptunite |
Locality: | California State Gem Mine (Benitoite Gem Mine), San Benito River headwaters area, Santa Rita Peak, New Idria District, San Benito County, California, USA | |
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Dimensions: | 28 cm |
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Face of specimen before work began |
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Mineral: | Benitoite and Neptunite |
Locality: | California State Gem Mine (Benitoite Gem Mine), San Benito River headwaters area, Santa Rita Peak, New Idria District, San Benito County, California, USA | |
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Dimensions: | 28 cm |
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Side of specimen, showing original thickness and final thickness. This was done using a tile saw to create parallel cuts (as seen in the garnet example) and then using an air scribe to make the bottom look more natural. |
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Mineral: | Benitoite and Neptunite |
Locality: | California State Gem Mine (Benitoite Gem Mine), San Benito River headwaters area, Santa Rita Peak, New Idria District, San Benito County, California, USA | |
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Dimensions: | 28 cm |
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Back of the specimen before matrix was reduced in thickness. |
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Mineral: | Benitoite and Neptunite |
Locality: | California State Gem Mine (Benitoite Gem Mine), San Benito River headwaters area, Santa Rita Peak, New Idria District, San Benito County, California, USA | |
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Dimensions: | 28 cm |
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After one trip in HCl to try to smooth out the hackly natrolite, some air scribing to remove natrolite and matrix on the face, and air abrasion to remove clays and remove film off of the crystals. The color of the matrix is better, and the benitoites and neptunites are cleaner. It now needs to have the dust washed off, and it is done. |
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Mineral: | Benitoite and Neptunite |
Locality: | California State Gem Mine (Benitoite Gem Mine), San Benito River headwaters area, Santa Rita Peak, New Idria District, San Benito County, California, USA | |
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Dimensions: | 28 cm |
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Close up of final specimen before washing. |
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Mineral: | Benitoite and Neptunite |
Locality: | California State Gem Mine (Benitoite Gem Mine), San Benito River headwaters area, Santa Rita Peak, New Idria District, San Benito County, California, USA | |
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Dimensions: | 28 cm |
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Pierre Joubert
Joined: 09 Mar 2012
Posts: 1605
Location: Western Cape
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Posted: Jul 14, 2015 13:01 Post subject: Re: Removing matrix using tile saw and air scribe |
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Job well done Bob!
_________________ Pierre Joubert
'The tree of silence bears the fruit of peace. ' |
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