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DrManhattenPhD

Identification: Black, smooth skin and transparent, transmits white light

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What do you mean by transmits white light?

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Even though the surface is black, when you shine a light through it, it appears white. One has some banding similar to an agate, but the other is purely white.

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I wonder if the black coating could be manganese which is typical in some areas. May I ask where you found it?

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Posted (edited)

Well.... according to this article, it belongs to the obsidian family and the description fits your specimen to a T. I've never seen any obsidian quite like this though.

https://www.meteorites-for-sale.com/saffordite.html

Here's another article.

https://www.tektites.info/obsidian

Edited by Morlock
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We have them exactly like that in New Mexico. But they are slightly green when backlit. Many are the "dog bone" shape of a tektite. Black and velvety and often with folds, wrinkles and creases. They are distinctly different shapes and texture than a "maerkanite" obsidian nodule found in volcanic ash but they are considered obsidian.

Many have "sheen" and banding. Some are almost perfectly clear when tumbled...only slightly smoky. You would think they were slightly tinted glass. For many years I have thought these little glass blobs could possibly be meteoritic and not volcanic because of their shape and folding. 

I have seen "Saffordite" specimens and I always thought that it was all the same stuff. I guess Saffordite does not have a tint when backlit and appears white. These little glass shapes are not white but decidedly green or grey. Other than that they are identical and these are considered "obsidian". Both (to me) appear to be slightly different than the average obsidian nodule.

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DSCN0713.JPG

Here is a little dark one for reference. I am going to start calling them "Crucite Tektites" and peddling them on Ebay.

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Posted (edited)
5 hours ago, Bedrock Bob said:

We have them exactly like that in New Mexico. But they are slightly green when backlit. Many are the "dog bone" shape of a tektite. Black and velvety and often with folds, wrinkles and creases. They are distinctly different shapes and texture than a "maerkanite" obsidian nodule found in volcanic ash but they are considered obsidian.

Many have "sheen" and banding. Some are almost perfectly clear when tumbled...only slightly smoky. You would think they were slightly tinted glass. For many years I have thought these little glass blobs could possibly be meteoritic and not volcanic because of their shape and folding. 

I have seen "Saffordite" specimens and I always thought that it was all the same stuff. I guess Saffordite does not have a tint when backlit and appears white. These little glass shapes are not white but decidedly green or grey. Other than that they are identical and these are considered "obsidian". Both (to me) appear to be slightly different than the average obsidian nodule.

Wait, you have something other than Apache Tears there? :o

Got a photo with more direct light? :D

 

AoxkMhm.png

Edited by DrManhattenPhD

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5 minutes ago, DrManhattenPhD said:

W5m201z.jpg

 

Real saffordite show pitting and dimpling like this. The first two photos at the top are not Saffordite.

Then maybe they are a clear phase of obsidian?

Many of the nodules I pick up here show dimpling just like that as well. Some are velvety and some are pitted/regmaglypt looking divots all over them. But I think that surface texture is common to many obsidian nodules and not just Saffordite.

What you have looks just like what I am finding here. The more translucent specimens would be impossible to differentiate by sight. I have always called them "obsidian" but there are obvious differences in clarity and color, texture and shape from standard obsidian nodules. 

If you put a handful of the clear ones on a lit surface they would look exactly like the photo above. What they are and what you have I don't know, but they are very similar.

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13 minutes ago, DrManhattenPhD said:

Wait, you have something other than Apache Tears there? :o

Got a photo with more direct light? :D

 

AoxkMhm.png

Yup. Those are standard "merkenites" in your photo. Ours are velvety and quite a bit softer. They all have a rounded, smoothed shape to them. None have smooth surfaces like a maerkanite and many if not most are translucent. Something that happens only once in a while in the smaller maerkanites. 

They are all found at the surface in little groups of four or six. Only on the hilltops. They break up easily and by the time they reach the toe of the hills they are just shattered flakes. They are all sitting on top of reworked gravels overlying caliche in several isolated spots in the area. 

They pretty much resemble an "Apache tear" and that is what everyone here calls them. But they are distinctly different than the standard maerkanite that comes form layers of volcanic mud. We have plenty of those too. And a whole mountains of obsidian and perlite. These may be a variation on the theme for sure. But they are not the standard maerkanite like in your photo above.

Ill post a photo of a handful this evening. I have tumbled a bunch that are almost as clear as glass. I think they formed as ejecta and solidified in the air rather than in a volcanic flow like a maerkanite. For all practical purposes they look exactly like the little Saffordite nodules in every way except some are darker green when light passes through. Others would be indiscernible from Saffordite. At least to my untrained eye.

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5 hours ago, DrManhattenPhD said:

W5m201z.jpg

 

Real saffordite show pitting and dimpling like this. The first two photos at the top are not Saffordite.

Maybe the two pieces at the top were tumbled, eliminating the pits?

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Posted (edited)

Tumbled without the polish step at the end? Maybe so. But, the weight would be way above average and the shape would still be wonky for Saffordite.

Edited by DrManhattenPhD

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Interesting material, the second photo looks like a pebble of black basalt which it obviously isn't. I don't know of any other rocks/minerals that appear that opaque and are as translucent as your your first image posted. Neat.

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4 hours ago, fuss said:

 I don't know of any other rocks/minerals that appear that opaque and are as translucent as your your first image posted. Neat.

Ditto

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7 hours ago, fuss said:

Interesting material, the second photo looks like a pebble of black basalt which it obviously isn't. I don't know of any other rocks/minerals that appear that opaque and are as translucent as your your first image posted. Neat.

IKR? I like them, but I want to know what they actually are. Maybe some kind of agate thats been river tumbled?

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Wow!!!  I’m just used to throwing rocks, I believe I will look closer before I do.

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It looks like sea glass. There is sea glass that glows when backlit form the manganese and or uranium. I don't know much about it because we don't find it here on our shores or rivers.

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On 8/22/2019 at 8:02 PM, DrManhattenPhD said:

Wait, you have something other than Apache Tears there? :o

Got a photo with more direct light? :D

 

AoxkMhm.png

 I don't know of any other rocks/minerals that appear that opaque and are as translucent as your your first image posted. Neat.

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