snuffy
Cave Dweller
Member since May 2009
Posts: 4,319
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Post by snuffy on Oct 29, 2013 19:57:57 GMT -5
As I look through my Brazilian slabs and pieces,I'm always on the lookout for anything unusual,and this caught my eye. One found tonight Anyway,interesting to me! snuffy
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Bennett
starting to shine!
Member since March 2009
Posts: 35
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Post by Bennett on Oct 29, 2013 20:20:34 GMT -5
I don't know for sure but I think you gotta rock tick climbing up that slab.
Bennett
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rolanstones
noticing nice landscape pebbles
Member since August 2013
Posts: 95
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Post by rolanstones on Oct 29, 2013 20:47:35 GMT -5
Too cool!!! A single teardrop, fell from the brilliant crystalline heavens, and traced its path before it remained frozen in the depths for all time......
OK, maybe I got a bit psychotropic there. I cannot imagine the forces that created that, so once again, TOO COOL !
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Deleted
Deleted Member
Member since January 1970
Posts: 0
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Post by Deleted on Oct 30, 2013 14:32:12 GMT -5
Dang Scott. That was as awesome as the original stone itself!
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Post by pghram on Oct 30, 2013 14:32:21 GMT -5
Neat slab, it would make a great specimen.
Rich
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quartz
Cave Dweller
breakin' rocks in the hot sun
Member since February 2010
Posts: 3,341
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Post by quartz on Oct 30, 2013 14:55:21 GMT -5
That's a really different formation, makes me wonder how things like that happen. Thanks for showing. Larry
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sheltie
freely admits to licking rocks
Member since January 2012
Posts: 982
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Post by sheltie on Oct 30, 2013 15:45:56 GMT -5
Looks like a Xmas ornament!
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Deleted
Deleted Member
Member since January 1970
Posts: 0
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Post by Deleted on Oct 30, 2013 17:22:34 GMT -5
Awesome rock cut in exactly the right place. From my studies in the making of agates that would be the entry point for all things flowing into the cavity. Don't quite understand the teardrop though. Jim
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carloscinco
fully equipped rock polisher
Member since July 2008
Posts: 1,639
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Post by carloscinco on Nov 1, 2013 18:34:27 GMT -5
Really cool waterline teardrop. The kind of stuff that gets that bull wheel turning in my head, stuff begins to spin and then I have to sit down for a spell.
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kaldorlon
spending too much on rocks
Member since October 2013
Posts: 413
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Post by kaldorlon on Nov 1, 2013 19:18:02 GMT -5
Sad Clown Brazilian!
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gemfeller
Cave Dweller
Member since June 2011
Posts: 3,813
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Post by gemfeller on Nov 1, 2013 20:56:17 GMT -5
That's fascinating. Those are called connection channels but there's disagreement as to how and why they form. Some researchers say they're left when silica-bearing solutions flow into the cavity where the nodule forms; others say they're for draining liquids externally. Following the proposals of Marco-Campos Venuti in his new book "Genesis and Classification of Agates and Jaspers: A New Theory," I suggest the bands in the "bubble" formed at the same time and from the same materials as the major bands. The interior of the nodule was plastic silica gel and liquid was flowing into the vent, creating the "bubble."
I've forwarded these images to Venuti. When (and if) he responds with an explanation I'll post it. Meanwhile, whatever the explanation of the origin, the structure is exotic and beautiful.
Rick
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grizman
freely admits to licking rocks
Member since July 2011
Posts: 878
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Post by grizman on Nov 1, 2013 21:27:35 GMT -5
Very simply, DOUBLE WOWWWZERS!
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Fossilman
Cave Dweller
Member since January 2009
Posts: 20,687
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Post by Fossilman on Nov 1, 2013 21:38:36 GMT -5
I like it...
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adrian65
Cave Dweller
Arch to golden memories and to great friends.
Member since February 2007
Posts: 10,777
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Post by adrian65 on Nov 2, 2013 1:41:13 GMT -5
That slab would make a very unique cab. Beautiful.
Adrian
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Post by mohs on Nov 2, 2013 12:00:18 GMT -5
good rock to the last drop ! mohs
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Post by mohs on Nov 2, 2013 12:00:31 GMT -5
good rock to the last drop ! mohs
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Post by 1dave on Nov 4, 2013 10:03:52 GMT -5
That's fascinating. Those are called connection channels but there's disagreement as to how and why they form. Some researchers say they're left when silica-bearing solutions flow into the cavity where the nodule forms; others say they're for draining liquids externally. Following the proposals of Marco-Campos Venuti in his new book "Genesis and Classification of Agates and Jaspers: A New Theory," I suggest the bands in the "bubble" formed at the same time and from the same materials as the major bands. The interior of the nodule was plastic silica gel and liquid was flowing into the vent, creating the "bubble." I've forwarded these images to Venuti. When (and if) he responds with an explanation I'll post it. Meanwhile, whatever the explanation of the origin, the structure is exotic and beautiful. Rick Beyond interesting! Structures like this provide insight (and a lot of wild guesses)on how our treasures come into being. We know "geodes" in basalt began as gas bubbles under intense pressure. As the gas cooled, the space it created became a vacuum chamber. Cooling basalt contracted and fractured allowing hot circulating fluids to be sucked in. That is when the interesting stuff - the "endothermic / exothermic dance" begins! High temperature minerals begin crystallizing in thermal order, BUT crystallization generates heat, stopping the current process and re-starting the previous one! This can cause color banding in plumes, or rhythmic banding in many minerals. Beautiful artistic stuff created and hidden away until we make lucky cuts and bring them into view. There has to be a temperature at which stuff stops crystallizing on crystal faces or on the cavity walls and begins forming horizontal layers on the floor, but I have never heard anyone experimenting and mentioning it. The "tick" was obviously fed by an early opening that the first layers curved to, then late in the process was among the last to be filled at a lower temperature. Thanks for sharing and stimulating the old grey matter! Dave
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gemfeller
Cave Dweller
Member since June 2011
Posts: 3,813
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Post by gemfeller on Nov 4, 2013 10:21:17 GMT -5
I did receive a rather enthusiastic response from Mr. Campos-Venuti this morning. You might want to think twice before you cab that specimen -- it could have scientific value. I'm posting his response here with a few changes for clarification since English is a second language to him. He mistakenly thought the slab was mine. Hi Rick, thank you very much for your exiting picture. Most of my job has been done on specimens and some structures are really rare and few of them talk to us about its geological history. Your slab is a rare channel filled up by plane banding. Never seen an other like this. The interpretation of that piece is by 4 steps: 1) the first chalcedony layer forms, stuck to the cavity walls (this portion is plastic and can undergo plastic deformation after deposition); 2) concentric banding forms, band by band, leaving a channel where the infiltration of water is easy (this portion is solid and can't undergo plastic deformation after deposition); 3) horizontal banding forms, filling the small cavity leaved open inside the channel (this portion is formed by slight dilution of the concentric bands and its re-deposition on the cavity floor); 4) quartz crystallizes in a concentric way. The 4 steps represent a sequence from a colloidal solution to a more diluted one. In term of time of deposition, the longer step is the 1) as indicated by more important thickness. Steps 2) to 4) are a relatively fast phenomenon. see you soon, marco Marco Campos-Venuti www.agatesandjaspers.comwww.rivistagemmologicaitaliana.it
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Post by pghram on Nov 4, 2013 10:35:35 GMT -5
Thanks for posting the slab & the explanation. You really can teach an old dog something new.
Rich
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Post by 1dave on Nov 4, 2013 11:11:44 GMT -5
I did receive a rather enthusiastic response from Mr. Campos-Venuti this morning. You might want to think twice before you cab that specimen -- it could have scientific value. I'm posting his response here with a few changes for clarification since English is a second language to him. He mistakenly thought the slab was mine. Hi Rick, thank you very much for your exiting picture. Most of my job has been done on specimens and some structures are really rare and few of them talk to us about its geological history. Your slab is a rare channel filled up by plane banding. Never seen an other like this. The interpretation of that piece is by 4 steps: 1) the first chalcedony layer forms, stuck to the cavity walls (this portion is plastic and can undergo plastic deformation after deposition); 2) concentric banding forms, band by band, leaving a channel where the infiltration of water is easy (this portion is solid and can't undergo plastic deformation after deposition); 3) horizontal banding forms, filling the small cavity leaved open inside the channel (this portion is formed by slight dilution of the concentric bands and its re-deposition on the cavity floor); 4) quartz crystallizes in a concentric way. The 4 steps represent a sequence from a colloidal solution to a more diluted one. In term of time of deposition, the longer step is the 1) as indicated by more important thickness. Steps 2) to 4) are a relatively fast phenomenon. see you soon, marco Marco Campos-Venuti www.agatesandjaspers.comwww.rivistagemmologicaitaliana.it Not so rare. Marco needs to visit the Geode Kid's collection at the Mimbres Museum in Deming New Mexico. He will see all kinds of stuff he has never seen before! 1) Plastic? I used to turn my car to the rising sun and watch the ice crystals pass through their transition points and start slumping or jump to the side as water drops. Very informative! 2) Rhythmic banding can occur over a short period with rapid changes in temperature, or separated over long periods with repeated in-fillings. 3. Horizontal banding as above, but at a lower temperature, often as water evaporates. 4) Quartz crystallizes as tetrahedra attach to each other, depending on temperature controlled bond attachments.
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