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Post by rockyraccoon on Feb 5, 2005 22:35:44 GMT -5
i am reading that rainbow obsidian is black obsidian cut at proper angles to prouce a rainbow of colors. does anybody know how this is done? is all rainbow obsidian black obsidian?
kim
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Post by cookie3rocks on Feb 5, 2005 22:57:38 GMT -5
I've seen some rainbow obsidian locally ( they wanted like $15.00 a lbs so I didn't go there) But it was black rough, it just had a prisim effect to it. Didn't seem to have anything to do with the cutting, this was broken chunks. Very, very pretty, in the rough at least.
cookie
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JKowalski33
spending too much on rocks
Member since August 2004
Posts: 451
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Post by JKowalski33 on Feb 5, 2005 23:05:20 GMT -5
from what i know, it has nothing to do with the way it is cut. What happens is as the molten rock cools, layers of micro bubbles form and once it is cool they somehow refract the light in different colors.
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Post by BearCreekLapidary on Feb 6, 2005 0:03:58 GMT -5
Hello Kim,
Not all black obsidian has the ability to show a variety of colors ... some is just plain black.
It was explained to me this way:
It is due to the impurities in the molten magma and how it cooled. It depends on what minerals/impurities were in the magma/air during the flow of this molten material and how it was cooled down.
There are a host of obsidians: black, snowflake, blue, green, red, gold, purple, clear, banded and a wide variety of multi colored obsidians - such as; rainbow, velvet sheen, aurora borealis, etc.
If you have even seen Mohogony Flow Obsidian ... you see varying layers of black, clear, and the mahogony reddish-brown colors. Sometimes in plain flat layers and some times in swirls ... depending on how it flowed as a molten magma and how it cooled. A lot of this material you can actually see through the clear layers that are bordered by eith black or mahogany - very unique stuff.
I have some of this material in my shop ... if I can find it I will make a cab and show you how the layers vary.
On the obsidian that does offer some color in the rough ... it depends on how you cut the rough as to how strong the colors show when slabbed. If you cut it at a 90 degree angle of the color band, you will not have much color. If you cut it as close to the color band as you can get without cutting through the band ... you will have a much more colorful slab of rock to work with.
It can be a pain trying to figure how the material formed and which way the color bands run ... so you do not cut through them at a 90 degree angle. The closer you are to the color bands ... the more light that is allowed to penetrate the obsidian and reflect/illuminate the color bands.
I also have some Aurora Borealis Obsidian in the shop as well, that I can photograph and show what I mean a little better.
Photo's will either be on Monday or Tuesday ... so, keep your eyes open.
Hope this helps,
John
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Post by rockyraccoon on Feb 6, 2005 1:39:12 GMT -5
on reading further maybe what i have isn't rainbow obsidian. what i have is a 9# piece of peacock obsidian. but i'm guessing the same principle will apply that if i don't cut it right it won't show the swirls and rainbows. it just looks black to me . kim
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Post by BearCreekLapidary on Feb 6, 2005 17:19:29 GMT -5
Hi Kim,
Peacock Obsidian is very pretty if cut correctly.
Are you able to tell which way the layers of color run? It can be tricky ... as sometimes the material with have swirls inside of the stone that you can not see.
If you can cut with the layers of color and not cut across them ... you should end up with some very pretty obsidian.
I have found that if I cut obsidian within a 10 degree angle of the color layers ... I will still get very nice color ... it is not as vibrant as cutting as close to the layers without cutting through them though.
You have a nine pound piece (GOOD SIZE!). You can do this and it will help you determine the color bands:
Cut a cube out of your chunk of rough. Trim as little as possible and come up with six sided cube/rectangle. That will allow you to see the banding on all six sides, and help you to determine on how to cut the chunk and get the most of the material.
Hope that helps,
John
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Post by krazydiamond on Feb 6, 2005 17:37:55 GMT -5
does obsidian cab well? i've tumbled some and it's a little pregnant dog. tricky stuff to get a shine on. anyway, i swore off it since then, but got a nice slab of mahogony obsidian in the mail and am wondering is there a tricky technique to cabbing it?
thanks for any input,
KD
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Post by rockyraccoon on Feb 6, 2005 18:54:42 GMT -5
kd these on e-bay look real good search.ebay.com/obsidian-cabochon_W0QQfkrZ1QQfnuZ1because it's soft it should be easy and use tin oxide to polish. i would think you'd want to definitely use your dust mask as glass up the nose can't be a good thing. john i think i can see the bands but the piece is not only heavy but sharp and i have to be careful handling it while i'm trying to turn it in the light. well duh i guess i could put on some work gloves lol. kim
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Post by krazydiamond on Feb 6, 2005 20:46:42 GMT -5
dust up the nose has made me the woman i am today (kidding)..
you got that saw cranked yet, Kim?
KD
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Post by rockyraccoon on Feb 6, 2005 22:59:47 GMT -5
yes i posted some pics of my 1st slabs under the post with the saw. i couldn't go play with the saw this weekend because it would be unfair to my daughter to make her go to the office on her time off from school but tomorrow i can!
kim
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Post by BearCreekLapidary on Feb 6, 2005 23:23:07 GMT -5
Hey KD, Personally ... I love obsidian I use my old stand-by polish (Cerium Oxide with Linde A) and it polishes up beautifully. Give it a try ... I think you will like the way it cabs ******************************************** Hey Kim, If I am handling rough (especially obsidian) I generally use leather gloves as well. It has save me from many cuts from the sharp edges of the obsidian. Hope this helps, John
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Post by rockyraccoon on Feb 7, 2005 0:08:16 GMT -5
john i actually cut my hand the day this material came in and within hrs it was sore, swollen, and red. antibiotic ointment was not helping by the next day. so i went to peroxide which cleared it right up and i will be more careful next time. i have never had that happen as many times as i have cut myself with the rocks.
kim
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Post by sandsman1 on Feb 7, 2005 0:51:03 GMT -5
KD heres a piece of obsidian i did it comes out nice but i had to go slow it likes to chip and i like to do a dry 220 belt on my cabs to get the bigger scratches out i can see them better when there dry but it kept messin it up it would get hot and crumble so mi had to redoit and use water on all grits then it came out ok,, it has fuzzies on it from the rag in the pic it realy did shine up great like glass
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