grayfingers
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Post by grayfingers on Jan 30, 2014 12:14:56 GMT -5
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Post by rockpickerforever on Jan 30, 2014 12:47:52 GMT -5
Oooh, cool! Bill, about how big are those nodules? Coupla inches? Really like the specimen candidate. So the secret to cutting agates is to candle them first? I found a 5 pounder while searching around our camp site at Quartzsite. Only a small bit of it was showing above ground, but I managed to spy it.
I'll have to soak/scrape the caliche off it before it can be candled, but I think it'll be a good'un. I can't see any visible fractures. It's soaking right now. (Oops, still have to clean off my saw and change the mineral oil...maybe even put the new blade on while I'm at it.)
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grayfingers
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Post by grayfingers on Jan 30, 2014 13:25:02 GMT -5
Jean, here is a size reference shot. They are as large as I can handle on the 7" saw, a new blade will cut a 3" nodule with a complete "roll of the stone". Nerve-racking though, trying to stay steady and smooth on the bigger ones. ![](http://i214.photobucket.com/albums/cc153/agates77/Lapidary%20One/Lapidary%202/Agates001sm_zps60f22c4c.jpg) Edit: Jean, about candling, I have only done it on Montana agates. I would think as long as there is enough translucence in the stone, it might help to candle. I use it to look for pattern and color, and fractures. Sometimes the skin is just too dark to tell what lies within. Then it is a matter of trying to look at the nodule and imagine which way the banding/ dendrites lie and make a cut. When one is too fractured for good slabs I tap them apart with a small sharp cold chisel, and then slabbette/cab from the solid pieces.
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jamesp
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Post by jamesp on Jan 30, 2014 13:39:24 GMT -5
Fine nodules Bill. The first one is dalmation. Those are superb Montanas.
When hunting agates in the end of the Rio Grande in south Texas i found worn agates like that. Makes you wonder if the coatings and junk was ground of and the toughest part was left. Can Montanas be found above glacier/erosion effects where they were initially formed? I guess that is called hillside material. Guessing those are biscuit shaped fills in volcanic flows. Also like the blue glow. Montanas do that best.
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Post by Hard Rock Cafe on Jan 30, 2014 13:54:43 GMT -5
All nice, but I really like the tubes in the last one. Bummer about the fractures. :-(
Chuck
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grayfingers
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Post by grayfingers on Jan 30, 2014 14:04:24 GMT -5
Can Montanas be found above glacier/erosion effects where they were initially formed? James, your question is one I wish I knew the answer to. As no one knows precisely where in the Yellowstone area the agates originated, or what/when forces freed them from the basalt, it is a conundrum to be sure. Also, the variety of formations (botryoidal, layer, banded...) seems to me to indicate different events/times of formation. I do know some areas I would like to prospect for in situ nodules. Thing is, I probably don't want to know... because if they exist, I believe they are in the higher reaches of the Park.
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gemfeller
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Post by gemfeller on Jan 30, 2014 15:02:43 GMT -5
I do know some areas I would like to prospect for in situ nodules. Thing is, I probably don't want to know... because if they exist, I believe they are in the higher reaches of the Park. The European discoverer of Yellowstone was John Coulter, a member of the Lewis & Clark expedition who decided to stay in the mountains and become a trapper instead of returning East. For years the place was known among the early Mountain Men as Coulter's Hell. Another trapper, Jim Bridger ("Old Gabe")probably did more to popularize the area than anyone in his time. Frustrated that Easterners wouldn't believe his tales of geysers and other volcanic marvels, he amused himself by telling really big whoppers about the place. If you're looking for in situ nodules you'll probably find them where Bridger said he saw "peetrified birds singin' peetrified songs in peetrified trees." Or near his cliff of pure volcanic glass (now called Glass Cliffs.) As Stanley Vestal tells it: "One day, Jim said, he sighted a bull elk, drew a careful bead on the critter, and pulled the trigger. The elk did not even raise his head from the grass to show that he heard the rifle crack. Still the elk grazed undisturbed. A third and fourth shot did no better. Jim was close now. He grabbed his rifle by the barrel, raised it like a club, and charged the elk. Suddenly he was brought up short, and found he had crashed into a mountain of clear glass. Through it he could still see the elk grazing. " 'Stranger still, the mountain was not only of pure glass, but was a perfect telescope lens, and whereas, the elk seemed but a few yards off, it was in reality, twenty-five miles away.' " Happy hunting! ![:)](//storage.proboards.com/forum/images/smiley/smiley.png)
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Post by rockpickerforever on Jan 30, 2014 16:45:18 GMT -5
Bill, those are bigger than I thought. Size of saw certainly is a limiting factor. I put that big agate on the scale, it's not 5 lbs, it's 7! May have to hook up with someone with a larger saw... I have no idea what the inside of AZ agates look like, but most probably not like Montanas. But I won't know until I cut one open. In addition to the big one, I brought home smaller ones as well.
And then there's the ones on my patio from two trips to Potholes! ¡Ay, caramba! I need to quit bringing this stuff home!
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jamesp
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Post by jamesp on Jan 30, 2014 17:14:52 GMT -5
The European discoverer of Yellowstone was John Coulter, a member of the Lewis & Clark expedition who decided to stay in the mountains and become a trapper instead of returning East. For years the place was known among the early Mountain Men as Coulter's Hell. Another trapper, Jim Bridger ("Old Gabe")probably did more to popularize the area than anyone in his time. Frustrated that Easterners wouldn't believe his tales of geysers and other volcanic marvels, he amused himself by telling really big whoppers about the place. Read more: forum.rocktumblinghobby.com/thread/64067/mt-nodules-2?page=1&scrollTo=723662#ixzz2rvEd101ZMr Rick, you would enjoy William Bartram's book about his travels in the south east. He was a biologist and was hired by England to accurate record what he saw. Late 1700's when native man was still in heavy occupation. Which he interfaced with a lot. I travel by boat and kayak many of his routes. Still very remote to this day. The abilities of native man and the size of gators and largemouth bass and many physical conditions. Bartram's travels are posted by road side signs all over the south east.
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jamesp
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Post by jamesp on Jan 30, 2014 17:34:34 GMT -5
James, your question is one I wish I knew the answer to Read more: forum.rocktumblinghobby.com/thread/64067/mt-nodules-2?page=1&scrollTo=723693#ixzz2rvIAS29DWe discussed several times where the agates come from. Things got shuffled a lot. So much Montana agate exists it amazes me the source may be shuffled to the point that the origin is unknown. Interesting when i collected in Texas i was doing hillside stuff like Woodrow, Alpine, Marfa etc. Then drove way east and south and found worn pebbles of what sure likes the same material(and many others of course) in the washed/moved down the Rio condition. That is when i learned how stuff moves around out west. You guys are used to that complex knowledge. Seems like my coral is sitting about where it was when it was alive. Different world.
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Fossilman
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Post by Fossilman on Jan 30, 2014 17:44:16 GMT -5
Love Montana Moss agate!!!! Great agate buddy,are those healed fractures I see... Man those really POP!!! Totally awesome!
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Fossilman
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Post by Fossilman on Jan 30, 2014 17:48:37 GMT -5
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gemfeller
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Post by gemfeller on Jan 30, 2014 18:37:46 GMT -5
Mr Rick, you would enjoy William Bartram's book about his travels in the south east. He was a biologist and was hired by England to accurate record what he saw. Thanks for the referral James. I just downloaded a copy to my Kindle. I think we all tend to focus on history of areas we're familiar with. I grew up in Idaho just a few miles south of Yellowstone. The geology of the region, combined with the fur trade history of the early 1800s, fascinated me. The fur trade was very much part of where I lived. I've done lots of research on both subjects over the years. Collecting and cutting Montana agate also dates back many years with me. I personally think Tom Harmon of Crane, MT has done as much research into Yellowstone River agate as anyone. An exerpt from his book "The River Runs North, A Story of Montana Moss Agate," dates the agate formation at 90 million years ago when Montana had heavy growths of redwoods and sequoias. The huge Yellowstone "hot spot" erupted, as it has many times over geologic history, and buried the trees in hot volcanic ash. Most of the wood burned leaving tree and limb-shaped cavities. In time rainwater bearing silica and other minerals from the volcanic ash slowly filled the molds with chalcedony. Then erosion eventually wore away the host rocks where the chalcedony was trapped and washed it down river, breaking it into chunks in the process then tumbling them into the shapes we find today. In my opinion they're not true agate nodules like the amydgules found in in some basalts. I strongly doubt any in situ MT agates can be found today but I've been wrong many times before. I've seen some amazing limb casts from the Gallatin Basin but they weren't the typical MT agate type. Because of the terrific pounding the agates have suffered from tumbling against other rocks, internally fracture-free Montanas are pretty unusual. Here's a slice from one I found long ago:
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jamesp
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Post by jamesp on Jan 30, 2014 19:14:47 GMT -5
Because of the terrific pounding the agates have suffered from tumbling against other rocks, internally fracture-free Montanas are pretty unusual. Here's a slice from one I found long ago: Read more: forum.rocktumblinghobby.com/thread/64067/mt-nodules-2?page=1&scrollTo=723718#ixzz2rvea3fKcTruly a lot of history and geology in that area. Of course it would be great if you could find Montanas in perfect shape. Interesting that they are probably limb casts. Some harsh conditions for rock out there. Amazing how things grind,wash, shift, up lift. A lot of fossils here are sitting about where they were when they were alive. Your conditions are complicated. And that is totally interesting. That is one of the few i have ever seen not fractured. We have much more limited earth resources. Thanks for the info.
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grayfingers
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Post by grayfingers on Jan 30, 2014 19:52:41 GMT -5
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carloscinco
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Post by carloscinco on Jan 30, 2014 21:12:42 GMT -5
Super Montana Aggies!
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Post by pghram on Jan 30, 2014 23:00:41 GMT -5
Nice nodules, that slice is amazing!
Rich
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