vance71975
freely admits to licking rocks
Member since September 2022
Posts: 760
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Post by vance71975 on Nov 23, 2022 4:26:52 GMT -5
I am running into a bit of a weird "opposite day Like problem". I am tumbling some Opal, which, we all know, fairly soft. One would thing, since its soft, shatters you tap it with a hammer, etc that it would cut fast and you would have to watch it like a hawk to make sure you dont over cut. WELLLLLLLL that is NOT the problem I am having. It is cutting and shaping EXTREMELY SLOW, like Slower than the Mexican Lace agate. With the mexican Lace agate, In 4 days, you could very clearly notice the cutting and rounding, and the slurry was noticeably thicker in 4 days. These Opals are barely cutting, the edges have rounded off some but No where near what they should have considering I am using 36/70 SiC Grit(A 1 to 5 mix of 36 grit and 46/70 grit). Honestly, I am totally confused on this one. Like I was super worried about over cutting and losing too much volume, but they seem to be barely cutting, tho the grit IS breaking down and is noticable finer than when I started. Anyone have any Ideas? Honestly, The only guess I have is that since they are so light of a stone, they are not putting enough weight on each other to trap the grit and cut effectivly, but that is honestly just an off the cuff guess. Anyone have any Idea?
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Post by vegasjames on Nov 23, 2022 6:26:21 GMT -5
Is this the opal I sent you as a gift? If so, most of it is relatively hard. Opal is rarely all silica and water. Opals often also have varying amounts of aluminum oxide picked up from either clays they form from or biogenic sources such as diatomaceous earth or radiolarians. The hardness of opals can vary due to their water content and/or aluminum oxide content. Shattering is not necessarily relative to hardness. You can easy shatter a diamond as well by striking it with a hammer. Opal is not a true solid, but rather a hardened gel. It does not become a solid until it water content starts to go below 3%, in which the opal will start transitioning by crystallizing in to some form of chalcedony. Common chalcedony, agate, jasper or chert/flint. If the opal dries slow and steady the gel has time to restructure itself maintaining more stability as the water content, which can be as high as 21% declines. If the opal dries too rapidly, such as suddenly being exposed to air or temperature variations the gel cannot restructure rapidly enough to stabilize and stresses and cracks set up in the opal. This is why some opal is so prone to fracturing or chipping. The opalized wood I sent you has been at, or very near the surface for a very long time, and therefore most of it has had plenty of time to stabilize as its water content declined. In addition, it was also dug up from a diatomaceous earth field, which means it also picked up some strengthening aluminum oxide. I have tumbled several large batches of this opal in 12 pound rotary barrels and in one of my UV-18 vibe tumblers with just water and opal. No grit, no polish, no ceramic or plastic beads for cushioning. And I have very little breakage of stones from stresses and cracks. After about a week I just have some minor opal mud from the grinding that I wash out and collect for another project.
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rocknewb101
fully equipped rock polisher
Member since October 2022
Posts: 1,368
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Post by rocknewb101 on Nov 23, 2022 8:47:50 GMT -5
Very interesting info about Opals vegasjames! I bought some off a website (rough stone) as some of the first rocks I ever bought. When hubby was cutting it for me to try and shape with the dremel it shattered and chipped, and honestly felt really soapy. It was strange, but I had a hell of a time getting it to really round and shape. The way it shattered and felt I would have thought it would have rounded up in no time. Thanks for sharing that info (and thanks for asking the question, @vance1975!!)
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Post by vegasjames on Nov 23, 2022 8:55:13 GMT -5
Very interesting info about Opals vegasjames ! I bought some off a website (rough stone) as some of the first rocks I ever bought. When hubby was cutting it for me to try and shape with the dremel it shattered and chipped, and honestly felt really soapy. It was strange, but I had a hell of a time getting it to really round and shape. The way it shattered and felt I would have thought it would have rounded up in no time. Thanks for sharing that info (and thanks for asking the question, @vance1975!!) I have cabbed a lot of the opalized wood from here in Nevada. It is not much different than cabbing agates and jaspers as far as grinding time, and it rarely breaks on me. Have had a few pieces though basically shatter while slabbing. Again really depends a lot on how rapidly the opal lost most of its water.
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Post by vegasjames on Nov 23, 2022 8:56:05 GMT -5
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rocknewb101
fully equipped rock polisher
Member since October 2022
Posts: 1,368
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Post by rocknewb101 on Nov 23, 2022 10:09:48 GMT -5
Those really turned out nice. So much variety there! I'm wondering if my quality of rock is poor. I don't know much about the site I ordered from, and then found this forum and the rock shed and the rest was history lol.
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vance71975
freely admits to licking rocks
Member since September 2022
Posts: 760
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Post by vance71975 on Nov 23, 2022 12:21:38 GMT -5
Is this the opal I sent you as a gift? If so, most of it is relatively hard. Opal is rarely all silica and water. Opals often also have varying amounts of aluminum oxide picked up from either clays they form from or biogenic sources such as diatomaceous earth or radiolarians. The hardness of opals can vary due to their water content and/or aluminum oxide content. Shattering is not necessarily relative to hardness. You can easy shatter a diamond as well by striking it with a hammer. Opal is not a true solid, but rather a hardened gel. It does not become a solid until it water content starts to go below 3%, in which the opal will start transitioning by crystallizing in to some form of chalcedony. Common chalcedony, agate, jasper or chert/flint. If the opal dries slow and steady the gel has time to restructure itself maintaining more stability as the water content, which can be as high as 21% declines. If the opal dries too rapidly, such as suddenly being exposed to air or temperature variations the gel cannot restructure rapidly enough to stabilize and stresses and cracks set up in the opal. This is why some opal is so prone to fracturing or chipping. The opalized wood I sent you has been at, or very near the surface for a very long time, and therefore most of it has had plenty of time to stabilize as its water content declined. In addition, it was also dug up from a diatomaceous earth field, which means it also picked up some strengthening aluminum oxide. I have tumbled several large batches of this opal in 12 pound rotary barrels and in one of my UV-18 vibe tumblers with just water and opal. No grit, no polish, no ceramic or plastic beads for cushioning. And I have very little breakage of stones from stresses and cracks. After about a week I just have some minor opal mud from the grinding that I wash out and collect for another project. Thanks man that explains a lot, its a mixed batch of green opal and some you sent and some from another member.
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Post by susand24224 on Nov 23, 2022 15:53:35 GMT -5
To simplify this, although I found vegasjames' explanation fascinating, opal is quartzy with more water. Soft? No. I've cabbed and tumbled quite a bit and although there is an occasional piece that shatters, for the most part it does well. There is a fair amount of diatomaceous earth in what I have, and when there's too much, it either doesn't polish well or disintegrates. It also takes an incredible shine! The extra cushioning is to prevent cracks, which it is prone to do, especially (in mine) in the browns and greens. I separate it from other rocks due to its light weight. The "strongest" grit I've used is 60/90 so can't speak to the coarser material.
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vance71975
freely admits to licking rocks
Member since September 2022
Posts: 760
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Post by vance71975 on Nov 23, 2022 16:02:03 GMT -5
To simplify this, although I found vegasjames' explanation fascinating, opal is quartzy with more water. Soft? No. I've cabbed and tumbled quite a bit and although there is an occasional piece that shatters, for the most part it does well. There is a fair amount of diatomaceous earth in what I have, and when there's too much, it either doesn't polish well or disintegrates. It also takes an incredible shine! The extra cushioning is to prevent cracks, which it is prone to do, especially (in mine) in the browns and greens. I separate it from other rocks due to its light weight. The "strongest" grit I've used is 60/90 so can't speak to the coarser material. To be fair, I was going by the numbers off a google search and I stopped reading too soon. I saw 5 mohs and stopped reading, ADHD thing, I missed that it was a range from 5 to 6.5. So I missed that it can be nearly as hard as agate.
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Post by vegasjames on Nov 23, 2022 20:24:28 GMT -5
To simplify this, although I found vegasjames' explanation fascinating, opal is quartzy with more water. Soft? No. I've cabbed and tumbled quite a bit and although there is an occasional piece that shatters, for the most part it does well. There is a fair amount of diatomaceous earth in what I have, and when there's too much, it either doesn't polish well or disintegrates. It also takes an incredible shine! The extra cushioning is to prevent cracks, which it is prone to do, especially (in mine) in the browns and greens. I separate it from other rocks due to its light weight. The "strongest" grit I've used is 60/90 so can't speak to the coarser material. Opal is not really quartzy. All forms of quartz are crystalline. And therefore, natural quartz is a mineral. Opals are amorphous (lacking crystalline structure) and therefore cannot be classified as a mineral. Instead, opal is classifies as a mineraloid.
As I mentioned before, opal is not even a true solid, but rather a hard gel, which is why it is prone to cracking if it loses water too fast.
The hardness of opal is mainly due to its aluminum oxide content. If the opal is formed simply from dissolved silica then it will not have a higher hardness. Opals formed from silica sources containing aluminum oxide such as clays and diatomaceous earth will have a higher hardness.
Stability of opal has several factors. Water content, aluminum oxide content and how rapidly it lost water. A higher water content can make the stone softer. A higher aluminum oxide content can make the stone harder. Too rapid of reduction in the opal's water content leads to stresses and cracks in the stone making it more prone to breakage.
As I mentioned earlier though, all chalcedonies (common chalcedonies, agate, jasper, chert/flint) are the dehydration product of opals. As the water content of opal drops below 3% the silica in the opal begins to crystallize forming chalcedony, which is a cryptocrystalline to microcrystalline quartz, but is no longer opal. Therefore, opal and chalcedonies can occur together. I actually find the two combined in the same stone frequently, and where I find opal I also often find chalcedonies. When the stone has both opal and chalcedony due to the transitioning, the stone will be too dense for opal, and too light for chalcedony as the stone gains density as water loss occurs in the opal. This will also increase the hardness of the stone due to the loss of water and crystallization of the stone in to a quartz.
Opals do seem to have varying stability based on colors as well. Most the opal I find is pretty solid and does not break easily. For some reason though the solid red opal I find is very fragile and I rarely find pieces larger than a dime. I have tried to cab some pieces of larger red opal I found but I kept having pieces chip out the face when I was almost done with the cab. I mainly collect the red because I think it would be a great substitute for red coral used in inlay with turquoise. Not sure why the red is so unstable since I have the same issue with the red found in different locations in the same area and all the other colors of opal in the same spot are stable I suspect it has something to do with the impurities giving it the color altering the nucleation that starts the opal formation process. For instance, it could have been some form of salt, and to much salt can mess with the opalization process.
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vance71975
freely admits to licking rocks
Member since September 2022
Posts: 760
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Post by vance71975 on Nov 23, 2022 21:53:14 GMT -5
To simplify this, although I found vegasjames' explanation fascinating, opal is quartzy with more water. Soft? No. I've cabbed and tumbled quite a bit and although there is an occasional piece that shatters, for the most part it does well. There is a fair amount of diatomaceous earth in what I have, and when there's too much, it either doesn't polish well or disintegrates. It also takes an incredible shine! The extra cushioning is to prevent cracks, which it is prone to do, especially (in mine) in the browns and greens. I separate it from other rocks due to its light weight. The "strongest" grit I've used is 60/90 so can't speak to the coarser material. Opal is not really quartzy. All forms of quartz are crystalline. And therefore, natural quartz is a mineral. Opals are amorphous (lacking crystalline structure) and therefore cannot be classified as a mineral. Instead, opal is classifies as a mineraloid.
As I mentioned before, opal is not even a true solid, but rather a hard gel, which is why it is prone to cracking if it loses water too fast.
The hardness of opal is mainly due to its aluminum oxide content. If the opal is formed simply from dissolved silica then it will not have a higher hardness. Opals formed from silica sources containing aluminum oxide such as clays and diatomaceous earth will have a higher hardness.
Stability of opal has several factors. Water content, aluminum oxide content and how rapidly it lost water. A higher water content can make the stone softer. A higher aluminum oxide content can make the stone harder. Too rapid of reduction in the opal's water content leads to stresses and cracks in the stone making it more prone to breakage.
As I mentioned earlier though, all chalcedonies (common chalcedonies, agate, jasper, chert/flint) are the dehydration product of opals. As the water content of opal drops below 3% the silica in the opal begins to crystallize forming chalcedony, which is a cryptocrystalline to microcrystalline quartz, but is no longer opal. Therefore, opal and chalcedonies can occur together. I actually find the two combined in the same stone frequently, and where I find opal I also often find chalcedonies. When the stone has both opal and chalcedony due to the transitioning, the stone will be too dense for opal, and too light for chalcedony as the stone gains density as water loss occurs in the opal. This will also increase the hardness of the stone due to the loss of water and crystallization of the stone in to a quartz.
Opals do seem to have varying stability based on colors as well. Most the opal I find is pretty solid and does not break easily. For some reason though the solid red opal I find is very fragile and I rarely find pieces larger than a dime. I have tried to cab some pieces of larger red opal I found but I kept having pieces chip out the face when I was almost done with the cab. I mainly collect the red because I think it would be a great substitute for red coral used in inlay with turquoise. Not sure why the red is so unstable since I have the same issue with the red found in different locations in the same area and all the other colors of opal in the same spot are stable I suspect it has something to do with the impurities giving it the color altering the nucleation that starts the opal formation process. For instance, it could have been some form of salt, and to much salt can mess with the opalization process.
Wow awesome write up dude! Serious question are you a geologist or scientist by training or did you learn this all on your own?
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Post by vegasjames on Nov 23, 2022 22:20:49 GMT -5
Opal is not really quartzy. All forms of quartz are crystalline. And therefore, natural quartz is a mineral. Opals are amorphous (lacking crystalline structure) and therefore cannot be classified as a mineral. Instead, opal is classifies as a mineraloid.
As I mentioned before, opal is not even a true solid, but rather a hard gel, which is why it is prone to cracking if it loses water too fast.
The hardness of opal is mainly due to its aluminum oxide content. If the opal is formed simply from dissolved silica then it will not have a higher hardness. Opals formed from silica sources containing aluminum oxide such as clays and diatomaceous earth will have a higher hardness.
Stability of opal has several factors. Water content, aluminum oxide content and how rapidly it lost water. A higher water content can make the stone softer. A higher aluminum oxide content can make the stone harder. Too rapid of reduction in the opal's water content leads to stresses and cracks in the stone making it more prone to breakage.
As I mentioned earlier though, all chalcedonies (common chalcedonies, agate, jasper, chert/flint) are the dehydration product of opals. As the water content of opal drops below 3% the silica in the opal begins to crystallize forming chalcedony, which is a cryptocrystalline to microcrystalline quartz, but is no longer opal. Therefore, opal and chalcedonies can occur together. I actually find the two combined in the same stone frequently, and where I find opal I also often find chalcedonies. When the stone has both opal and chalcedony due to the transitioning, the stone will be too dense for opal, and too light for chalcedony as the stone gains density as water loss occurs in the opal. This will also increase the hardness of the stone due to the loss of water and crystallization of the stone in to a quartz.
Opals do seem to have varying stability based on colors as well. Most the opal I find is pretty solid and does not break easily. For some reason though the solid red opal I find is very fragile and I rarely find pieces larger than a dime. I have tried to cab some pieces of larger red opal I found but I kept having pieces chip out the face when I was almost done with the cab. I mainly collect the red because I think it would be a great substitute for red coral used in inlay with turquoise. Not sure why the red is so unstable since I have the same issue with the red found in different locations in the same area and all the other colors of opal in the same spot are stable I suspect it has something to do with the impurities giving it the color altering the nucleation that starts the opal formation process. For instance, it could have been some form of salt, and to much salt can mess with the opalization process.
Wow awesome write up dude! Serious question are you a geologist or scientist by training or did you learn this all on your own? Not a geologist. Been in medicine 44 years, and my dad is an inventor and my great grandfather was an inventor so I was brought up with inventing and love experimenting with stuff. One of my projects I have been working on for a number of years is trying to mimic nature to form opal. Been able to make common opal, which is pretty easy. Have not pulled off precious opal yet, but think I am getting a lot closer. Because of this project have done a ton of research on opal and have numerous files of information on opal including studies on opal formation.
Contrary to what geologists claim, opal does not take millions of years to form. Opal formation is actually extremely rapid. And opal can be made at home within a year including growing and drying to stabilize.
In fact, there are modern reports of opal formation such as the buried portions of wooden fence posts opalizing. Obviously these fence posts were not there for millions of years. And there is a story of a miner's cat that died. The miner wrapped the cat in a felt hat and put the dead cat in the opal mine. The mine was closed for around 50 years before being sold. The new owners found the opalized skeleton of the cat that had opalized as pink opal.
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vance71975
freely admits to licking rocks
Member since September 2022
Posts: 760
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Post by vance71975 on Nov 23, 2022 22:25:20 GMT -5
Wow awesome write up dude! Serious question are you a geologist or scientist by training or did you learn this all on your own? Not a geologist. Been in medicine 44 years, and my dad is an inventor and my great grandfather was an inventor so I was brought up with inventing and love experimenting with stuff. One of my projects I have been working on for a number of years is trying to mimic nature to form opal. Been able to make common opal, which is pretty easy. Have not pulled off precious opal yet, but think I am getting a lot closer. Because of this project have done a ton of research on opal and have numerous files of information on opal including studies on opal formation.
Contrary to what geologists claim, opal does not take millions of years to form. Opal formation is actually extremely rapid. And opal can be made at home within a year including growing and drying to stabilize.
In fact, there are modern reports of opal formation such as the buried portions of wooden fence posts opalizing. Obviously these fence posts were not there for millions of years. And there is a story of a miner's cat that died. The miner wrapped the cat in a felt hat and put the dead cat in the opal mine. The mine was closed for around 50 years before being sold. The new owners found the opalized skeleton of the cat that had opalized as pink opal.
Awesome, Watched a dude on youtube who made a precious opal in a lab, cool stuff for sure!
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Post by vegasjames on Nov 23, 2022 23:35:39 GMT -5
Not a geologist. Been in medicine 44 years, and my dad is an inventor and my great grandfather was an inventor so I was brought up with inventing and love experimenting with stuff. One of my projects I have been working on for a number of years is trying to mimic nature to form opal. Been able to make common opal, which is pretty easy. Have not pulled off precious opal yet, but think I am getting a lot closer. Because of this project have done a ton of research on opal and have numerous files of information on opal including studies on opal formation.
Contrary to what geologists claim, opal does not take millions of years to form. Opal formation is actually extremely rapid. And opal can be made at home within a year including growing and drying to stabilize.
In fact, there are modern reports of opal formation such as the buried portions of wooden fence posts opalizing. Obviously these fence posts were not there for millions of years. And there is a story of a miner's cat that died. The miner wrapped the cat in a felt hat and put the dead cat in the opal mine. The mine was closed for around 50 years before being sold. The new owners found the opalized skeleton of the cat that had opalized as pink opal.
Awesome, Watched a dude on youtube who made a precious opal in a lab, cool stuff for sure! Yes, they are doing it in an unnatural way though using a manmade chemical called TEOS. Very dangerous stuff to play with, and very expensive and hard to obtain. The process is pretty straight forward. A mix of TEOS, 30% ammonium hydroxide and usually ethanol heated then allowed to cool forms the opal. They usually dry it too fast though causing it to fall apart. And I have seen them try things like epoxy stabilization. Would not be very cost effective to make opal on a large scale.
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vance71975
freely admits to licking rocks
Member since September 2022
Posts: 760
|
Post by vance71975 on Nov 24, 2022 0:06:47 GMT -5
Awesome, Watched a dude on youtube who made a precious opal in a lab, cool stuff for sure! Yes, they are doing it in an unnatural way though using a manmade chemical called TEOS. Very dangerous stuff to play with, and very expensive and hard to obtain. The process is pretty straight forward. A mix of TEOS, 30% ammonium hydroxide and usually ethanol heated then allowed to cool forms the opal. They usually dry it too fast though causing it to fall apart. And I have seen them try things like epoxy stabilization. Would not be very cost effective to make opal on a large scale. True, still cool as hell to watch tho lol
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