Henry
spending too much on rocks
Member since January 2013
Posts: 452
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Post by Henry on Dec 15, 2017 23:51:13 GMT -5
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Post by fernwood on Dec 16, 2017 0:21:06 GMT -5
Here is some info: www.gemdat.org/gem-43544.htmlLooks like what I found with a simple image search. Does this have any flash? Know some of this material does and some doesn't.
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Post by rmf on Dec 16, 2017 6:09:11 GMT -5
there are two colors of andean opal that I know of blue and pink. Neither have fire but have nice blue and pink color. some with dendrites. I could not tell from the image if it was Opal or Chryscolla but there are just some details that an image just can't capture. like looking at it in person and looking for the luster, fracture etc. Andean Opal takes a great polish and looks good. hope you enjoy cutting it.
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Post by Bluesky78987 on Dec 16, 2017 22:01:00 GMT -5
Yup, that's a classic Peruvian Blue Opal. No play of fire. From the Andes, although haven't heard it called that. This one is bluer than most - more chrysocolla in it. The greyish part and the brownish part, in layers, are hallmarks. This looks just like what I saw in Tucson a couple years ago. It's very soft, but works up just fine in my experience.
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Henry
spending too much on rocks
Member since January 2013
Posts: 452
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Post by Henry on Dec 16, 2017 22:37:09 GMT -5
Thank you everyone! Bluesky78987: I had a funny feeling there was a Chrysocolla connection. Knowing very little about the aforementioned, I have a sample of chrysocolla, and I said to myself..."hmmm. the chrysocolla and the Peruvian blue opal sue look alike." My friend in Germany (the one that sent me the samples) called the the opal "chrysopal"?
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gemfeller
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Post by gemfeller on Dec 16, 2017 23:27:20 GMT -5
This material from Peru is quite variable. The opal is often intermixed with chrysocolla-colored gem silica. I'd recommend a hardness test to determine the nature of the deep blue parts of your specimen. Any silicated parts will be much harder than opal or chrysocolla. The image below is typical of the opal color from that source. Ignore the marks on it -- they're ink showing me the direction of a crack I plan to saw through to get clean pieces for cutting one of these days. There are some black dendrites on the bottom of the rough. I have images of a Peruvian gem silica cab somewhere in my photo archives. I'll post it if I can find it. The color is quite different than the blue-green opal.
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Post by Bluesky78987 on Dec 17, 2017 20:56:53 GMT -5
I would be interested in seeing different variations of the blue opal. I saw stuff like his picture at tucson, as well as pieces that had more of an "opal" look to them by having more whitish patches and milky opaque light blue. gemfeller, are you saying that they call lots of different things Peruvian Blue Opal? That piece of yours looks a whole lot like a super clear chrysoprase. I bought a piece of chrysopal once, it looked like your picture, if you added in a bunch of milk and whipped it up (with a bunch of voids and irregularities). Didn't cab well.
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gemfeller
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Post by gemfeller on Dec 17, 2017 21:31:58 GMT -5
I would be interested in seeing different variations of the blue opal. I saw stuff like his picture at tucson, as well as pieces that had more of an "opal" look to them by having more whitish patches and milky opaque light blue. gemfeller , are you saying that they call lots of different things Peruvian Blue Opal? That piece of yours looks a whole lot like a super clear chrysoprase. I bought a piece of chrysopal once, it looked like your picture, if you added in a bunch of milk and whipped it up (with a bunch of voids and irregularities). Didn't cab well. No, at least judging from the batch I've worked with. The piece in the image I posted is 100% what they call Peruvian blue opal, though most I've worked with is bluish-green not true blue. I think some is a stronger blue however. The names used for gems change so quickly, especially trade names, it's hard to keep up. The name "chrysopal" seems misleading to me though it may be colored by nickel like chrysoprase so it could be accurate in that sense. I have some green opal from Macedonia that likely has nickel as its chromophore. But it's opaque, not translucent. The Peruvian copper mines produce a range of materials: regular chrysocolla, blue opal, gem silica and a chrysoprase-like chalcedony some are calling chrysoverde. I have images of all those and if I can get a little time tomorrow away from Holiday Honey-Do's I'll post images. I don't claim to be an expert on the above materials but I've worked with all of those mentioned so have a few insights.
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Post by Bluesky78987 on Dec 17, 2017 22:03:52 GMT -5
Cool! Interested to see the images! Chrysoverde is a great name.
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gemfeller
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Post by gemfeller on Dec 18, 2017 13:54:28 GMT -5
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Post by Bluesky78987 on Dec 18, 2017 14:17:06 GMT -5
Interesting! Thanks for the explanation and the pictures. That green is an interesting color - almost a little bit mossy or something.
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Henry
spending too much on rocks
Member since January 2013
Posts: 452
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Post by Henry on Dec 20, 2017 0:05:06 GMT -5
Absolutely beautiful samples! So if I understand everyone correctly, the darker the blue...the more chrysocolla? Sorry to sound so repetitive, but I have very little knowledge in this area.
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gemfeller
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Post by gemfeller on Dec 20, 2017 19:22:32 GMT -5
Absolutely beautiful samples! So if I understand everyone correctly, the darker the blue...the more chrysocolla? Sorry to sound so repetitive, but I have very little knowledge in this area. Henry , I don't know the answer to your question. I'm not aware of any analytic work that's been done on these materials so I can't say whether intensity/saturation of color is proportional to the percentage of the mineral present. This gets into fairly complex areas of chemistry and mineralogy. Maybe someone else can help out on this.
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