carloscinco
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Post by carloscinco on Nov 20, 2009 20:05:39 GMT -5
I've read descriptions of petrified wood that include the word "opal". My guess is it may refer to a chalcedony like light colored part of the wood. Or.. are we talking about real opal?
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Deleted
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Post by Deleted on Nov 20, 2009 20:52:35 GMT -5
Its real opal, called "common" opal or even opalite at times. Common opal as opposed to precious opal, meaning its missing the fire that precious opals have. It comes in many colors, from white to blue to green. Unfortunately, it is often unstable and very fractured. Richardson Ranch thundereggs for instance will sometimes contain common opal. Ive got some nice blue and green. But as typical, its very fractured and can only be worked by making very small cabs......like those for earrings. It can command a decent price if its good quality though. Like Mexican Opal. Some have fire in them but others are just a plain orange, clear or other color. A high quality Mexican Opal with no fire can still fetch a decent price as it makes for an interesting cab or piece of jewelry when cabbed with the matrix.
Shan
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Deleted
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Post by Deleted on Nov 20, 2009 20:57:01 GMT -5
Oh, forgot to mention.........precious opal is also found in things like pet wood and dino bone on occasion. Imagine a slab where all of the cells have been replaced by fire opal. Its beautiful!!!
Shan
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carloscinco
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Post by carloscinco on Nov 20, 2009 21:17:30 GMT -5
Thanks for the help and the mental image. sigh.
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Sabre52
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Post by Sabre52 on Nov 21, 2009 0:26:31 GMT -5
Carlos: Yep, when I hunted wood around several areas in Nevada, almost all was common opal rather than jasper or agate and most all was heavily fractured. Far as I know, all the fire opal at the mines in Virgin Valley, NV is also opalized wood but I've seen lots of common opal wood from there too.....Mel
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MikeS
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Post by MikeS on Nov 21, 2009 16:02:18 GMT -5
You can have a combination of both opal and agate in the same specimen...sometimes in clearly defined layers or in more subtle transitions... the white bands in these limb casts are opal... These specimens are more blended, but mostly opal...
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Fossilman
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Post by Fossilman on Nov 23, 2009 9:41:00 GMT -5
I have a fossilized scaphite that has opal in its inner chamber,,,,,,,,,,,,,,,,Light blue in color. I had it split open(sawed) and the guy wanted to buy it on the spot! (ha ha)..No deal I said,it must be nice if you want to buy it-LOL
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Post by roswelljero on Nov 23, 2009 10:39:21 GMT -5
Opal is hydrated quartz, right? How do you identify it? How do you tell it apart from chalcedony, etc.?
Later, jeri
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Deleted
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Post by Deleted on Nov 23, 2009 13:46:20 GMT -5
scratch test for one......opal is much softer than agate/chalcedony.
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Post by Woodyrock on Nov 24, 2009 3:35:55 GMT -5
When you look at the broken surface of opal, it has a plastic look to it for a visual check.
BTW, most opal is basically unstable. Before the Chinese started buying all the opal they could get from Australia, the miners left freshly mined opal on the surface of the ground for a year. The buyers would not buy it otherwise. That is not so anymore. All the Oz opal fields have areas know to be unstable, and areas that are known to be stable. Since it is very difficult to tell what part an opal comes from in any given field fresh opals can be a real gamble if the seller is not honest.
A lot of people dismiss the common opals as junk, but I have seen some cabs that are real beauties made from the opal from the George, Wa, diamaetious earth pit material. Woody
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Post by roswelljero on Nov 25, 2009 1:15:04 GMT -5
Thanks! I've always wondered.
Later, jeri
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rockhound97058
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Thundereggs - Oregons Official State Rock!
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Post by rockhound97058 on Nov 25, 2009 23:56:41 GMT -5
Woody - Wish I had digital pics to share for the list... I have several 35mm photo's of my trips to the Diatom Pits... It's crazy up there... Veins of opal that are feet thick and run for 100's of feet! Many people claim it's opalized coral which makes sense as Diatoms are inland sea critters.
I used to collect opal there and make spheres from it. Some is junk, but have seen some outstanding colors/patterns.
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swordfishmining
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Post by swordfishmining on Dec 8, 2009 15:09:54 GMT -5
For a lot of opal in wood pictures from Virgin Valley see my Swordfish Mining website. I notice opal has a square fracture more than agates glass like one.
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jspencer
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Post by jspencer on Jul 20, 2012 15:42:42 GMT -5
Here are some Texas samples with partially opalized wood and a very hard but cool flint nodule. The opalized part seems pretty solid. Attachments:
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Post by 3rdrockfromthefun on Jul 20, 2012 16:36:32 GMT -5
Just scored a 1lb hunk of limb cast with blue/green opalite making up nearly it's entire mass and have another with nice brown/tan in it a bit smaller. Woody nailed it - it looks plastic - to me even so on unbroken surfaces.
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Post by jakesrocks on Jul 20, 2012 17:26:19 GMT -5
If I can find the right basement box, I'll get some pics of diatom pit opalized wood.
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herchenx
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Post by herchenx on Jul 20, 2012 22:53:23 GMT -5
Here is a piece of pet wood with a large bit of common opal on the top/left by my thumb. I posted about this a few weeks back after doing some hounding in south-central Wyoming. I saw some pieces that were incredible picked up there. daharsh.net/s/IMG_20120604_084745.jpg [/img]
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