tribeunited
fully equipped rock polisher
Not all materials look exactly the same. But all exact materials are exactly the same.
Member since May 2024
Posts: 1,909
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Post by tribeunited on Jul 24, 2024 15:55:04 GMT -5
Agatey bubbles of opaly substance. I thought fire opals, but those are labeled and stored in jars of liquid. These are kept in little bags. Fire agate - thanks amygdule
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Post by rockjunquie on Jul 24, 2024 15:57:45 GMT -5
Looks like fire opal to me. Beautiful!
It's a different kind of opal.
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tribeunited
fully equipped rock polisher
Not all materials look exactly the same. But all exact materials are exactly the same.
Member since May 2024
Posts: 1,909
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Post by tribeunited on Jul 24, 2024 16:01:44 GMT -5
So here's a fire opal question - why are some of them kept in jars of liquid? Are they less stable or do they dry out?
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Post by amygdule on Jul 24, 2024 16:03:53 GMT -5
Fire Agate...
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tribeunited
fully equipped rock polisher
Not all materials look exactly the same. But all exact materials are exactly the same.
Member since May 2024
Posts: 1,909
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Post by tribeunited on Jul 24, 2024 16:06:46 GMT -5
Thanks amygdule for the fire agate name. I'm not sure what to call these, I credited both names because they both seem right LOL I wonder if fire agate is commonly called fire opal, but is actually different from the jarred fire opals....
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Post by cabby on Jul 24, 2024 16:23:48 GMT -5
I agree on fire agate. Beautiful ones, too! Most of mine have very little to no fire…
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realrockhound
Cave Dweller
Chucking leaverite at tweekers
Member since June 2020
Posts: 4,354
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Post by realrockhound on Jul 24, 2024 16:28:07 GMT -5
Fire agate.
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Post by rockjunquie on Jul 24, 2024 16:37:03 GMT -5
Ooooops! I meant to say fire agate. Those are really top shelf.
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Post by Pat on Jul 24, 2024 16:45:07 GMT -5
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RWA3006
Cave Dweller
Member since March 2009
Posts: 4,571
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Post by RWA3006 on Jul 24, 2024 16:47:02 GMT -5
Fire agate.
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tribeunited
fully equipped rock polisher
Not all materials look exactly the same. But all exact materials are exactly the same.
Member since May 2024
Posts: 1,909
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Post by tribeunited on Jul 24, 2024 17:04:38 GMT -5
Thanks all - I'm the only one who didn't know LOL Ok when we say good ones - I've got some that look like the ones above and then these kind with top bubbles. Is there a difference??
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Post by cabby on Jul 24, 2024 17:08:59 GMT -5
Personally, I feel that any fire agate that has more than a tiny spot of fire is good 😆 but for grading the color of fire and amount of it are the most important, I think. Most of the time you won’t know how good it is until it’s been processed. Haven’t worked it myself, yet, but that’s what I’ve learned from watching far too much YouTube! Need to very slowly and carefully grind off little bits at a time to get down to the fire without grinding through it
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tribeunited
fully equipped rock polisher
Not all materials look exactly the same. But all exact materials are exactly the same.
Member since May 2024
Posts: 1,909
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Post by tribeunited on Jul 24, 2024 17:17:44 GMT -5
Thanks cabby! I wont even try to grade anything, I'll take the majority consensus and call it a day usually.
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realrockhound
Cave Dweller
Chucking leaverite at tweekers
Member since June 2020
Posts: 4,354
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Post by realrockhound on Jul 24, 2024 17:48:38 GMT -5
Agate fire opal
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Post by cabby on Jul 24, 2024 17:58:05 GMT -5
My collection shows some good examples of what’s NOT good! One has a well carved area, but so little of it. The back to are both ground through the fire layer in some places. The final pic you showed looks like the fire layer is already damaged, so the “usable” area ends up being much smaller. edit: btw I didn’t carve these, but tossed some bits into the picture to show what kind of tools are used to do so.
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Post by vegasjames on Jul 24, 2024 18:02:06 GMT -5
It is fire agate, which is not really agate by definition. Fire agate is a botryoidl chalcedony stained with iron salts such as goethite that can crate the iridescent rainbow effects. The layer is very thin, and it is easy to grind through that later when cabbing, so you need to be careful when cabbing it.
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Post by vegasjames on Jul 24, 2024 18:18:22 GMT -5
So here's a fire opal question - why are some of them kept in jars of liquid? Are they less stable or do they dry out? Some opals need to be kept in water until stabilized y very slow water reduction to keep them from crazing (cracking).
Opals are not true solids, they are an amorphous (lacking crystalline structure) gel. Since they are not truly solid, the molecules are still mobile. As the opal loses water, the molecules must restructure in to a new, stable arrangement. If the opal loses water faster than the molecules have time to reach a stable arrangement, the opal cracks.
For example, I have found several opalized logs here in Southern Nevada, but only find small pieces because they were exposed to the surface too rapidly, probably from being uncovered by floods. This did not give them time to decrease their water content slowly, and the result was severe cracking leading to small pieces. I have other pieces of opalized wood from Northern Nevada that I dug out from just under the ground that are much larger because with the remaining under the soil, and more moisture in the area, the opal was allowed to stabilize more by very slowly reducing water content.
Opal dug out from deeper in the Earth generally need to be kept in water, until they are stabilized. One common method of doing this is to wrap the opal in wet paper towels then seal in a couple of ziplock bags and place somewhere in a temperature constant location for 1 to 2 years. The water from the paper towels and opal will slowly dissipate out of the plastic bags allowing the gel molecules to stabilize as the water decreases. Does not work every time, but mot the time. Higher initial water contents or lower aluminum oxide content in the opals make them less stable and more probe to crazing.
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tribeunited
fully equipped rock polisher
Not all materials look exactly the same. But all exact materials are exactly the same.
Member since May 2024
Posts: 1,909
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Post by tribeunited on Jul 24, 2024 18:21:07 GMT -5
Wow - thanks for that very good explanation vegasjames! I get it!
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RWA3006
Cave Dweller
Member since March 2009
Posts: 4,571
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Post by RWA3006 on Jul 24, 2024 18:28:32 GMT -5
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gemfeller
Cave Dweller
Member since June 2011
Posts: 4,029
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Post by gemfeller on Jul 25, 2024 12:24:45 GMT -5
I have a little experience with fire agates. I spent an entire summer acquiring rough and learning to cut it. It's a very difficult material to master and I'm far from that level. As vegasjames correctly points out, it's chalcedony, not agate, as conventionally defined, and it often has what I call "opal bottoms" which for some unknown reason (to me) usually yield exceptional cut stones in my experience. These are roughs that have a layer of common opal (no play of color) attached. Fire agates from differing locations have distinctive characteristics. Most of my work involves stones from Slaughter Mountain and Deer Creek AZ thoggh I've also cut a fair amount from the Aguascalientes region of Mexico. The image is of a Deer Creek stone I cut and made a gold setting for. I have lots of cut stones if anyone would like to see images.
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