Deleted
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Member since January 1970
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Post by Deleted on Jan 1, 2019 19:45:17 GMT -5
I read that the snow flake effect is caused by rain drops falling on a previous ash covered flow and the water spots being formed when incorporated with the following flow. If that made sense ? Problem with that is that the white crystals often are found deep within the flow, rather than on the surface. Same thing with Snowflake obsidian. Unlike most agate which builds up in sequentially deposited layers, obsidian is extruded in thick masses. The layers and swirls are the result of minerals picked up along the way up from the depths, not from layering or interaction on the surface (though occasionally you'll find a rock embedded on the bottom of a piece. Cristobalite is the result of devitrification (crystallization of silca within the amorphous obsidian glass) rather than little shatters from rain causing rapid cooling. Hydration and other weathering of obsidian also leads to devitrification, though on the exposed outer surfaces and leads to a different sort of appearance (dull, rocky look) that forms a rind. Left on its own, obsidian does eventually completely devitrify into cristobalite or perlite. That is why obsidian is only found in regions with more recent volcanism.
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Post by woodman on Jan 1, 2019 21:47:20 GMT -5
A couple more that will show some nice sheen.
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Post by MsAli on Jan 1, 2019 22:36:02 GMT -5
Beautiful! I love how each one is so different
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NRG
fully equipped rock polisher
Member since February 2018
Posts: 1,630
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Post by NRG on Jan 2, 2019 9:20:42 GMT -5
The snowflakes in snowflake obsidian are sanidine feldspar. It makes good sense that an actual granite component would crystallize out in a slower melting material. This is confirmed by Don Kasper with ir crystallography.
It also lines up with a statement that snowflakes are often found in greater abundance in the center of stones. That would be the slowest cooling section, allowing for crystals to form.
Ali, I don't think your white spots are a flaw. I think they are a feature.
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Post by MsAli on Jan 2, 2019 10:49:23 GMT -5
Your guys knowledge of stuff amazes me What would cause the color when the light hits it? Not sure if you can see the spots of color? You cant tell by the picture, but it does also have some sparkle to it.
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NRG
fully equipped rock polisher
Member since February 2018
Posts: 1,630
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Post by NRG on Jan 2, 2019 11:56:03 GMT -5
Ali.
If you speak of a shimmer of color(s) then we call that sheen. I can't remember what sheen is formed by but I believe it is tiny crystals lined up like millions of little prisms.
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Post by MsAli on Jan 2, 2019 12:09:17 GMT -5
Ali. If you speak of a shimmer of color(s) then we call that sheen. I can't remember what sheen is formed by but I believe it is tiny crystals lined up like millions of little prisms. I have gold and silver and rainbow obsidian, but I've never seen obsidian with these kind of color spots It is really kind of fascinating to me I just cant wait to polish a piece and see what it comes out like
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NRG
fully equipped rock polisher
Member since February 2018
Posts: 1,630
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Post by NRG on Jan 2, 2019 13:03:24 GMT -5
There is "fire" obsidian too. Woodman would be able to tell you if he collected fire before.
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Post by MsAli on Jan 2, 2019 13:09:58 GMT -5
There is "fire" obsidian too. Woodman would be able to tell you if he collected fire before. I would literally faint if it was and then I would have to send it back to him
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NRG
fully equipped rock polisher
Member since February 2018
Posts: 1,630
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Post by NRG on Jan 2, 2019 13:36:05 GMT -5
There is "fire" obsidian too. Woodman would be able to tell you if he collected fire before. I would literally faint if it was and then I would have to send it back to him Try a cut WITH the flow lines.
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Post by MsAli on Jan 2, 2019 13:46:12 GMT -5
I would literally faint if it was and then I would have to send it back to him Try a cut WITH the flow lines. That's how I cut it initially
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NRG
fully equipped rock polisher
Member since February 2018
Posts: 1,630
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Obsidian
Jan 2, 2019 14:15:41 GMT -5
via mobile
Post by NRG on Jan 2, 2019 14:15:41 GMT -5
Try a cut WITH the flow lines. That's how I cut it initially The cut in the picture shows a cut across the lines. Imagine the blade following the lines; in between them.
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Post by MsAli on Jan 2, 2019 14:27:11 GMT -5
Bear with me while I get the image in my head Cut picture 1 or 2?
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Post by woodman on Jan 2, 2019 14:41:14 GMT -5
Glad you are having fun with it, It will be interesting to see what you end up with. While I have collected obsidian at Glass Buttes and out of Hines, this piece came from an estate sale pile of rocks the wife bought a number of years ago that started the expensive hobby!!
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Post by MsAli on Jan 2, 2019 15:07:11 GMT -5
Glad you are having fun with it, It will be interesting to see what you end up with. While I have collected obsidian at Glass Buttes and out of Hines, this piece came from an estate sale pile of rocks the wife bought a number of years ago that started the expensive hobby!! Thank you! Have you ever found any fire out there?
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Post by woodman on Jan 2, 2019 15:23:41 GMT -5
Glad you are having fun with it, It will be interesting to see what you end up with. While I have collected obsidian at Glass Buttes and out of Hines, this piece came from an estate sale pile of rocks the wife bought a number of years ago that started the expensive hobby!! Thank you! Have you ever found any fire out there? No fire, but I only covered a very small area and I did not know what I was looking for at the time.
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Post by MsAli on Jan 2, 2019 15:37:15 GMT -5
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Post by woodman on Jan 2, 2019 16:49:09 GMT -5
One heck of lot of information, years ago I was Elk hunter est of Seneca and found new road that was just pushed open, all the rock along the road was Obsidian, I put a lot of it in the back of my truck, I gave it all to a brother and he made a wall out of it, just stacked, will have to retrieve a piece or two and see what it is. I think it was all black but hard to tell without cutting it. I had forgot all about that until I was looking thru the information on Oregon sites. thanks for the link!
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Post by MsAli on Jan 2, 2019 16:51:59 GMT -5
One heck of lot of information, years ago I was Elk hunter est of Seneca and found new road that was just pushed open, all the rock along the road was Obsidian, I put a lot of it in the back of my truck, I gave it all to a brother and he made a wall out of it, just stacked, will have to retrieve a piece or two and see what it is. I think it was all black but hard to tell without cutting it. I had forgot all about that until I was looking thru the information on Oregon sites. thanks for the link! You are very welcome I haven't had elk in years! I love elk and barley soup I was trying to find information on how you can tell from the outside what it is, but haven't found anything
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Post by MsAli on Jan 2, 2019 16:54:21 GMT -5
Obsidian Color Pure obsidian is a very dark color. It gets this color from the presence of iron and magnesium. Colorless obsidian is rare. Mahogany obsidian has dark-brown to black and red banding. Sheen obsidian is dark-brown to black with a golden or silver sheen (this is also called aventurescence). Rainbow obsidian is dark-brown to black with an iridescent sheen. The iridescence of obsidian can be gold, silver, blue, violet, green or combinations of these colors. The rainbow colors of rainbow obsidian come from the presence of augitic pyroxene. "Fire" or "flame" obsidian reflects bright colors due to the presence of nanometric magnetite crystal layers. Transparent pale yellow-green to brownish obsidian from Peru is referred to as macusanite. Translucent to opaque, black-streaked orange, red or brown obsidian nodules from the American Southwest are known as "Apache tears". Orange obsidian is referred to as "pumpkin obsidian" and plum-colored obsidian is called "plum obsidian".
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