kyoti
has rocks in the head
Member since June 2020
Posts: 542
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Post by kyoti on Jul 2, 2020 21:48:51 GMT -5
Decided this morning to set my vibe to running a rough grind on a local rock I like to collect. It's a kind of chert with calcite and aragonite in it. Is a fairly soft stone but doesn't fracture easily. Very unassuming in the rough form and mostly appears tan or grey. Once it tumbles, colors and patterns appear like magic after stage 1. I call it my Surprise chert. Here is a picture of the tan rough. Here's a couple of pictures after stage 1. Here' are some greys. Bad tumble, I know but it was my first batch.
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Post by fernwood on Jul 2, 2020 22:21:17 GMT -5
Nice chert. It can be beautiful on the inside.
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Fossilman
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Member since January 2009
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Post by Fossilman on Jul 3, 2020 11:15:33 GMT -5
Nice tumbles..
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Post by miket on Jul 3, 2020 11:24:41 GMT -5
I like them. You can't judge a rock by it's cover...
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kyoti
has rocks in the head
Member since June 2020
Posts: 542
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Post by kyoti on Jul 3, 2020 14:50:21 GMT -5
Thanks for the compliments:) I have the little guys in the 600 grit today. It's quite a tough stone for something that rounds so easily. (Maybe I'm too used to trying to whip rebellious agate into shape.)
I've never heard of anyone trying to polish the chert. I was astonished the first time I used some as filler and saw all the colors suddenly appear. I did a little happy dance! I also have a bunch of honey colored chert disks I collect that are filled with shells. I'll try those next, I think.
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Post by TheRock on Jul 3, 2020 15:00:35 GMT -5
Nive Tumbles!
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Post by RocksInNJ on Jul 8, 2020 20:03:47 GMT -5
Wow what a nice surprise indeed. Especially for running the rough in a vibe.
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kyoti
has rocks in the head
Member since June 2020
Posts: 542
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Post by kyoti on Jul 9, 2020 7:51:32 GMT -5
Thank you! Yes they actually round quite easily. They appear to run between 4-6 mohs depending on each stone's mix of calcite crystal. I've run into some problems in the AO prepolish though. The aluminum particles have embedded themselves into some of the calcite veins. It's a bummer. I'm hoping I can do a burnish or Borax run to remove it.
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jamesp
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Member since October 2012
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Post by jamesp on Jul 30, 2020 6:19:55 GMT -5
Thank you! Yes they actually round quite easily. They appear to run between 4-6 mohs depending on each stone's mix of calcite crystal. I've run into some problems in the AO prepolish though. The aluminum particles have embedded themselves into some of the calcite veins. It's a bummer. I'm hoping I can do a burnish or Borax run to remove it. Did you have AO embed in the rocks in a rotary or vibe kyoti ? Normally this happens if the batch gets dry. Or too much AO is added. A decent rule of thumb is 1/2 cup of AO pre-polish for 10 pounds of rock in a rotary. About 2 tablespoons for 8 pounds in a vibe. Middle Georgia kaolin clay is dead white, and is composed of about 30% natural aluminum oxide of no telling what grit size. It also has silica/quartz sand particles. It is often refined to remove the silica but only the 200 grit silica and larger making it not such a good pre-polish candidate. Point being I avoid using the white kaolin as a step 1 slurry thickener because it overdoses with aluminum oxide and often gets jammed in fractures(or some component of the aluminum rich clay). For some reason iron stained kaolin(Georgia red clay lol) does not do this when used as a step 1 slurry thickener. I have had problems with Borax getting embedded in rocks in the vibe on numerous occasions if the batch dried out. So bad in fact I had to redo the batch from the start to remove the impacted Borax. grrr. I switched to using sugar in the vibe. It dissolves out of the fractures easily and allows white AO to release too.
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kyoti
has rocks in the head
Member since June 2020
Posts: 542
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Post by kyoti on Jul 30, 2020 17:44:46 GMT -5
jamesp It became imbedded while running the 1000 grit AO in the vibe. It was very hot during the week I was doing vibe runs and I was delayed coming home from work that day. When I got home, everything was piled up in one section of the bowl. The other side was dried out like you said. I was very disappointed. I ended up trying a borax and ivory soap shavings wash in the bowl for an hour. It worked really well and saved the rocks! It stripped most of the shine off but I can always rerun them later. They actually look pretty good with a satin finish. I ordered a new bowl and lid from Kingsley North this week to replace the old top that I had on my TV-5. That should help prevent things drying out again. I'm just finishing up the 600 grit in my rotary on a batch of agates I found locally. They'll be the next set that I'll try to polish in the vibe. Is the 1000 grit really neccessary or should I avoid it on soft rocks? Still learning I'm dying to try my creek glass someday.
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jamesp
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Post by jamesp on Jul 31, 2020 15:37:28 GMT -5
jamesp It became imbedded while running the 1000 grit AO in the vibe. It was very hot during the week I was doing vibe runs and I was delayed coming home from work that day. When I got home, everything was piled up in one section of the bowl. The other side was dried out like you said. I was very disappointed. I ended up trying a borax and ivory soap shavings wash in the bowl for an hour. It worked really well and saved the rocks! It stripped most of the shine off but I can always rerun them later. They actually look pretty good with a satin finish. I ordered a new bowl and lid from Kingsley North this week to replace the old top that I had on my TV-5. That should help prevent things drying out again. I'm just finishing up the 600 grit in my rotary on a batch of agates I found locally. They'll be the next set that I'll try to polish in the vibe. Is the 1000 grit really necessary or should I avoid it on soft rocks? Still learning I'm dying to try my creek glass someday. That was a bad day. Drying a batch is about always not good. You were fortunate that you were able to clean out the compaction. Soft rocks do well with more steps. Hard agates break grit down faster than say glass or soft rhyolite due to their shear hardness. I can do agates in 3 steps easily. Even in 2 steps. Glass takes 4 steps because it is softer. I have not found a way to do glass in 3 steps but have tried. And I have to run glass in the vibe with quartz pea gravel media to assist breaking the abrasives down. The glass will break down the abrasives but it takes a long time. Just thinking about tumbling soft calcite for instance. It would be a challenge for Mohs 3 calcite to have much ability to break down Mohs 9 silicon carbide - not going to happen. Only choice is to add more steps of finer and finer abrasive. More overlaps of sizes so to speak. I know for a fact my AO 220 breaks down to AO 2000-3000 running glass with quartz. That surely reduces the amount of abrasive steps. Dry tumbling probably requires more steps since it is not likely the abrasives are going to break down in such a situation. A possible alternate is using a softer abrasive for softer rocks. Like diatomaceous earth, iron oxide, garnet, pumice, etc..
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Post by greig on Jul 31, 2020 17:47:54 GMT -5
I really like the artistic nature of the pic in the sieve. Kinda like a ta-daaa!
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kyoti
has rocks in the head
Member since June 2020
Posts: 542
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Post by kyoti on Aug 2, 2020 17:40:13 GMT -5
I really like the artistic nature of the pic in the sieve. Kinda like a ta-daaa! Thanks! I'm hoping to have another nice surprise soon. I'm running a set of new rocks I find locally. It looks like a purple Basalt that's filled with white polka dots
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Post by rockjunquie on Aug 2, 2020 21:06:52 GMT -5
I really like the artistic nature of the pic in the sieve. Kinda like a ta-daaa! Thanks! I'm hoping to have another nice surprise soon. I'm running a set of new rocks I find locally. It looks like a purple Basalt that's filled with white polka dots Purple AND polka dots? My ears just perked up.
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Post by hummingbirdstones on Aug 2, 2020 21:56:14 GMT -5
Thanks! I'm hoping to have another nice surprise soon. I'm running a set of new rocks I find locally. It looks like a purple Basalt that's filled with white polka dots Purple AND polka dots? My ears just perked up. So did mine.
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lookatthat
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Post by lookatthat on Aug 4, 2020 15:40:16 GMT -5
Hmmm. I picked up a load or two worth of chert-like stuff in WV a couple years ago. I don't think it will be as pretty as yours, but maybe I'll give it a try.
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kyoti
has rocks in the head
Member since June 2020
Posts: 542
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Post by kyoti on Aug 5, 2020 19:47:48 GMT -5
Hmmm. I picked up a load or two worth of chert-like stuff in WV a couple years ago. I don't think it will be as pretty as yours, but maybe I'll give it a try. Don't let the ouside colors scare you away. You never know what they'll look like until the outer shell comes off. Here's some pics of the purple basalt rough. Heres some stained ones that I thought looked pretty cool playing garden border.
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