ejs
spending too much on rocks
Member since July 2008
Posts: 478
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Post by ejs on Apr 7, 2009 16:00:17 GMT -5
Howdy hey. Another month, another batch ready. :-) I've often admired the carnelian agate that I've seen others post on this forum. So last fall, I went looking on eBay for a nice chunk. Here is the one that I purchased: image1:  I purchased this one because I liked the red/caramel color. As you'll see, that color didn't really come out in the final rock. Last November, I smashed up the big piece with a mini sledgehammer: image2:  The more astute among you will notice a lot of fractures introduced by that method, many of which will show up in the final product: image3:  Next time, I'll use my tile saw to avoid introducing such fractures. I ran them via my usual method: repeated 5-day rounds of coarse in 60/90 SC in a 6 lb. Lortone. The carnelian proved to be quite hard and took quite a while to smooth out. Here is how it looked in January, after 7 rounds of coarse: image4:  Once smooth, I ran my usual formula, ending with 2 weeks in cerium oxide polish. Here are the final results. I am quite pleased with the rounded and smooth shape of the rocks and I got a pretty killer shine: image5:  image6:  image7:  Say cheese! image8:  Although its hard to tell from straight on, the rock has some nice internal striping : image9:  image10:  My wife liked the stripes so much that she suggested I find a way to turn these into a wind chime window mobile. Great idea! Any help? :-) I'm not particularly fond of the color of this rock. What I had in mind was much more red/orange/rust, whereas this rock is brown/blue. I tossed in one piece from another source (from a mixture) and ran it through the same process. This is much more like the color I had in mind: image11:  I also tossed in one piece from a large chunk or red/black agate that I have tumbling in separate barrels. I'll have two barrels worth of this stuff done in about two weeks. image12:  All in all, I'm quite pleased. The two things I would change: - start with better material that is much more red. Any suggestions for sources of good carnelian? - use the saw instead of the hammer to avoid fractures As always, thanks for looking, and any comments are always gratefully received. |
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NorthShore-Rocks
fully equipped rock polisher
Member since December 2008
Posts: 1,004
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Post by NorthShore-Rocks on Apr 7, 2009 16:10:28 GMT -5
You certainly obtained a killer shine! Thanks for the other tips too!
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Post by parfive on Apr 7, 2009 16:57:08 GMT -5
Great lookin' batch, Ejs. Especially the banded ones.
Rich
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MikeS
fully equipped rock polisher
Member since January 2009
Posts: 1,081
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Post by MikeS on Apr 7, 2009 17:07:51 GMT -5
those look great!
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Saskrock
fully equipped rock polisher
Member since October 2007
Posts: 1,852
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Post by Saskrock on Apr 7, 2009 17:24:32 GMT -5
They look great, but I don't think I could have brought myself to hitting that chunk with a hammer. Your a more dedicated tumbler than me.
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carloscinco
fully equipped rock polisher
Member since July 2008
Posts: 1,639
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Post by carloscinco on Apr 7, 2009 18:56:40 GMT -5
Have you wondered what half a day in a toaster oven would do to that color? I'm sure someone here has recommended roasting times and temps.
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ejs
spending too much on rocks
Member since July 2008
Posts: 478
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Post by ejs on Apr 7, 2009 19:01:16 GMT -5
Okay, Carlos, that's a new one! I'm not sure if you are joking or not...
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Saskrock
fully equipped rock polisher
Member since October 2007
Posts: 1,852
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Post by Saskrock on Apr 8, 2009 0:34:17 GMT -5
I have read the cooking thing too. I think its supposed to intensify the color.
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tom
having dreams about rocks
Member since March 2009
Posts: 50
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Post by tom on Apr 8, 2009 6:51:05 GMT -5
Awesome shine ejs.
Cooking rocks..? Hmm...interesting. Might be my next experiment.
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ejs
spending too much on rocks
Member since July 2008
Posts: 478
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Post by ejs on Apr 8, 2009 8:40:31 GMT -5
I have a bunch of this carnelian, so I am willing to give it a try, if someone has a recipe and I am convinced that this isn't some practical joke y'all play on the newbies! :-)
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Post by frane on Apr 8, 2009 8:49:34 GMT -5
That is some beautiful Carnelian, even if it is not red as you would like. I have seen the cooked stuff and it really brings out the colors. May be a good experiment. I would also cut that chunk up next time so you don't get so many fractures. It is worth a try.
Was it Mel that posted how to cook it or someone else? I just can't remember.
Fran
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huffstuff
fully equipped rock polisher
Member since August 2007
Posts: 1,222
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Post by huffstuff on Apr 8, 2009 12:05:42 GMT -5
Killer shine! I like the more orange carnelian, too. Has anyone found that cooking recipe...?
Amy
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rockerfellerz
starting to spend too much on rocks
Member since August 2008
Posts: 120
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Post by rockerfellerz on Apr 8, 2009 19:36:59 GMT -5
Great batch! I really like carnelian, and you got some real good results with that stuff. I like the color, but yeah, a brighter orange/red would be even nicer.
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reelman
starting to spend too much on rocks
Member since July 2008
Posts: 114
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Post by reelman on Apr 8, 2009 22:06:09 GMT -5
Great looking shine. It is tough to find carnelian that is red or deep orange all the way thru. Most of the deeper color is on the surface and much paler inside. Smaller pieces have the best chance of color in the middle.
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rockwizz
freely admits to licking rocks
Member since May 2007
Posts: 971
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Post by rockwizz on Apr 8, 2009 23:54:07 GMT -5
Really pretty stuff. Looks like the big chunk was a big piece of Brasilian? I really love those brasilians, the colors is unmatched. They take a while to polish but they are worth it.
Thanks for sharing.
Ozzy
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lapidopterix
starting to spend too much on rocks
Member since March 2008
Posts: 216
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Post by lapidopterix on Apr 9, 2009 0:04:23 GMT -5
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ejs
spending too much on rocks
Member since July 2008
Posts: 478
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Post by ejs on Apr 9, 2009 8:01:24 GMT -5
Thanks for the link, lap. I will definitely try this and post the results! The big difference is that I will be working with rocks that are already polished. I wonder if they'll need a new round of polish after the heating?
Stay tuned for pics!
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colliel82
has rocks in the head
Member since November 2007
Posts: 664
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Post by colliel82 on Apr 9, 2009 11:25:41 GMT -5
Love the pics. Especially the ones where you can see the reflections so clearly. Can't wait to see the heat treated results.
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chadman
starting to spend too much on rocks
Member since March 2008
Posts: 106
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Post by chadman on Apr 9, 2009 11:29:58 GMT -5
I doubt it will hurt the finish. Try it. Hmm. I have a kiln for glass fusing. I refitted it with a computer recently. Matter fact it's cooling down after a slump fire last night. I'll go home at lunch to see how it came out. I can ramp those temps pretty easy. Looks like they are trying to achieve a slow ramp to evenly heat the rock. The silica sand would be used to help evenly heat the rock while ramping the temperature slowly up, but more important to slow the cooling rate down by holding the heat to prevent thermal shock from cooling too fast. That way you can get it to 550 and then shut it off and let it cool naturally. The silica will hold the heat. There was someone that visits this site that I met and Ricahrdson's Rock Ranch that was doing something similar with yellow jasper. He was making arrowhead points and then heat treating them in a fire pit, hots rocks and sand. I think he said they turned a lavender or purple color if I recall correctly. I forgot his name. He told me that's the way the Indians did it I think. Nice fellow. A kiln with a computer can do that much more precisely by programming a rate of temp increase and decrease. The sand would not be needed. If you know anyone or have a local glass artist, I would ask them to test fire them at a rate of 100 to 125 degrees per hour to 550 degrees, hold for 1 hour and then ramp down at the same rate to 70 degrees. Do some bartering with them. Or send me a couple test samples, I'll try it and you can barter with me  Most of the time I do this kind of stuff just for the knowledge. |
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Post by 150FromFundy on Apr 9, 2009 15:37:16 GMT -5
On the side topic of "cooking", here is what I little I know about it.
In the case of Citrine (yellow quartz), iron is the element which gives citrine its warm golden color. Extreme heat, whether naturally occurring or applied by man, will turn Amethyst (purple quartz) into a burnt golden color. Technically, Citrine is "burnt" Amethyst. In fact, much of the cheap Citrine available (especially from Brazil) is really cooked Amethyst. Look for purple Amethyst flecks (inclusions) in your next Brazilian Citrine purchase.
So, if it works for Quartz (SiO2 with impurities) it should also work for your Carnelian Agate (SiO2 with impurities). The downside is, I believe the necessary "extreme heat" could only be achieved by an industrial kiln.
If I'm wrong about the oven, please let me know. I like to bake when I'm not playing with rock.
150FromFundy
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