|
Post by helens on Jan 10, 2013 4:31:44 GMT -5
I read that they were 'quenching' even sapphires (bit pricier than carnelian), here's a reference: www.gemologyonline.com/treatment.htmlFrom the last paragraph of the 'dying' section: "I recently encountered strands of sapphire beads which were quench cracked and died. The treatment was easily visible with microscopic observation, but it did not bleed at all when soaked in acetone." Then I found this very neat article on jade dying (and quenching)!! www.viennoisjewellery.com/?p=17And... making synthetic sapphires/rubies appear real via quenching (synthetics are still 9 MOH): www.gemstones-guide.com/Testing-Synthetic-Gemstones.html"A particularly troublesome synthetic ruby or sapphire is one that been "quench crackled" (Figure p). This is done by heating a polished stone and plunging it in to cold water or a saturated solution, from which the chemical crystallizes in the cracks formed by quenching, giving arborescent forms to the deposit. Sometimes, the heated stone is immersed in a dye, which imparts color. A stone treated in this manner appear to have natural inclusions and fractures and thus be misidentified, particularly if it is cut in one of the styles used for natural stones. The practice has been used for a number of years to falsify solitaire size stones, but more recently it has been used for imported calibre-cut stones. Usually, the appearance of the cracks in larger stones is recognized by experience. Magnification generally discloses curved striae or growth lines or bubbles, as in ordinary synthetics. The importer of calibre sizes has a more difficult task in separating crackled stories from large lots of natural rubies or sapphires. Especially troublesome stones, both large and small, should be immersed in methylene iodide, to minimize the effect of the cracks while searching for identifying inclusions. Another suggested test is to use the shortwave ultraviolet unit and note the greater fluorescence of the synthetic when observed in a dark room." Apparently, Quenching stones has been around quite some time and employed in very sneaky ways!!!
|
|
|
Post by helens on Jan 10, 2013 4:40:07 GMT -5
Ok, now I'm REALLY curious... if I remember, I'll try it tomorrow with a few small sacrifice pieces of agate. If you don't hear from me for a few days, I'm probably in the hospital from flying shrapnel. LOL!
|
|
|
Post by gingerkid on Jan 10, 2013 9:57:06 GMT -5
|
|
|
Post by rockpickerforever on Jan 10, 2013 11:01:13 GMT -5
I remember waaaaay back, when I was a kid, we used to take marbles (anything but opaque), put them in a pan of water, and heat it on the stove. When they were hot, you'd take them out and drop them into a glass of cold water. Instant crackle! Funny, I don't remember any of them breaking up into little bits like safety glass. It seems they always remained in one piece. Jean
|
|
|
Post by helens on Jan 10, 2013 12:35:36 GMT -5
That could be temperature related... my thought was to flash the agate through the back of the torch and quench. If it doesn't crackle, I'll apply more heat and do it again. Will try it later this afternoon:).
When I quench glass, it's usually molten. Molten borosilicate is 1750 degrees minimum. Boiling water is 212 degrees. THAT may be the key... will try it at a much lower temp:)!!
|
|
|
Post by helens on Jan 10, 2013 12:40:39 GMT -5
Also... why can't the process be natural too?
If all it takes is boiling water temp (which does not exceed 212 degrees), dropped down to cold water temps (say 40 degrees), that's only a 130 degree difference in temps... a SUDDEN warm/cool could concievably do that... probably where a lot of natural cracks in glass come from, and heck, SOME of them just got lucky and had a more even chilling so they crackled all over... but it's rare:)?
|
|
|
Post by rockpickerforever on Jan 10, 2013 12:59:05 GMT -5
Ya think?
I used to have a large (4 X 8 foot) glass topped table on my patio. It was over a half inch thick. During the winter months, the sun is at such a low angle that it shines quite a bit onto the patio. Several years ago, we had a night where the temp dipped below freezing (kind of what we are expecting tonight!), and the next morning the sun came out and hit that glass -CRAAAACK! And it was not safety glass. Also had a table top with fossils in it, which had a resin coating (bought in Quartzsite!). The sun also cracked a portion of the coating off of it. So from below freezing to maybe 60 or 70 degrees? While the temp difference would obviously matter, I think the suddeness of it is the key factor.
For the most part, nothing happens suddenly in geology, but there are a few instances, such as a molten lava flow reaching the ocean. Could glass-like bombs be ejected from a volcano, and quench quickly in the sea and crackle? I suppose anything is possible. Jean
|
|
Deleted
Deleted Member
Member since January 1970
Posts: 0
|
Post by Deleted on Jan 10, 2013 13:40:59 GMT -5
Take another close look at the first picture. I remember the craze (pun intended) for quench-cracked marbles, and the thing that also sticks out in my memory is that you never played with them afterwards (they'd fall apart once hit even lightly during a game). Glass is a non-crystaline material, and quench-cracking produces a random pattern. Similarly, cryptocrystaline agate produces a conchoidal and random crazing pattern when quenched, as there is no large-enough crystal structure to follow. I'm not seeing a random pattern in the OP photos at all, nor a botryoidal formation that causes turtleback pattern in agate (no crisp, outlined edges in turtleback agate). The distinct edges to the 5-to-6-sided "cells" look far more like the outlines of crystal twinning surfaces you would expose when slicing through the base of a crystal cluster (which would rule out the pattern being formed by a cryptocrystaline material such as agate). I also am not seeing any evidence of agate banding anywhere. As suggested before, it could be a pseudomorph (chalcedony, etc.) replacing something else, but you'll have to determine what is in those "cells." The cracked "gem" materials are often done after shaping, but are also heavily treated with other heating processes (including the introduction of glass filling and colorant) that somewhat glues them back together. I suggest doing some further scratch testing beyond the metal items, as that doesn't even get you halfway through the range of hardnesses. Be certain not to press too hard (which give misleading pressure-flaking marks rather than a true scratch) and compare your results to any of the mineral hardness tables online, such as this one on geology.com
|
|
|
Post by tntmom on Jan 10, 2013 14:38:50 GMT -5
I took the slab, cleaned it up and did a quick polish on both sides with my flat lap. I should have spent more time on the 325 disk but it took a very high gloss polish. These pictures were taken with indoor lighting at my desk: Backlit Front side: Back side:
|
|
|
Post by rockpickerforever on Jan 10, 2013 14:47:32 GMT -5
So, it didn't fall apart... It looks great! I'm still leaning towards natural. Glad to see you put Cody back up for your avatar Who is the pretty kitty? Jean
|
|
|
Post by tntmom on Jan 10, 2013 15:11:07 GMT -5
Jean, Thats my Ragdoll Tessa. She's 6 years old and she lays claim to every box of rocks I get (cell phone picture)
|
|
|
Post by helens on Jan 11, 2013 12:58:20 GMT -5
Beautiful cat Krystee!!!
Ok, experiment done, but I have to run out the door, will post a thread about it later tonite:).
|
|
|
Post by helens on Jan 11, 2013 13:23:17 GMT -5
|
|
|
Post by helens on Jan 12, 2013 17:23:25 GMT -5
Something dawned on me that I should have thought of yesterday. I think Daniel and Rock2Dust tried to tell me this, but I wasn't getting it.
If you heat/quench a rock... those are OPEN FISSURES necessarily... meaning that you are counting on the cracks NOT closing to maintain the structural integrity of the rock. If the cracks are actually open cracks (in the case of being able to absorb dye, as the method suggests), even if the cracks are under the surface, the rock is inherently weak, because those are open cracks, even if very thin.
So the key question is... are the fractures in Krystee and Rocks2Dust's rocks SEALED? If so, then they occurred a long time ago, and no different from any other healed fractures, and could have cracked from heat/cooling, then filled in with agate (like dino bone). If still open, they could have been produced with heat. As far as I know, there's no sealant that is MOH 7 hardness, so the rock would not have the same physical integrity as say dino bone, which is pure filled in agate.
That also leads to another obvious assumption I completely missed... they HAVE to have sealed the 'dragon scale' agate somehow to be able to work it.
|
|
|
Post by tntmom on Jan 12, 2013 17:38:16 GMT -5
Helen,
When I grinded and polished the slab it was completely solid. I could not get any non-healed fractures to show up on the surface of either side of the slab. The only thing marring the finish is some 325 grit scratches that I left because I was in a hurry to polish it.
|
|
|
Post by helens on Jan 12, 2013 18:34:28 GMT -5
In that case, I'd say your piece was natural Krystee. I'm wishing I could find more details on the entire quenching process, but usually, treating imitates a rare natural phenomenon (and usually much inferior to nature). What you and Rock2Dust have may be something really rare and precious in the rock world, because you just do not see it often at all.
LETS SEE THIS CAB!!!!
|
|