My Archaeological Find: Calling all rock geeks!

i don't think it is glass. it is too angular looking to be melted glass.

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this message has probably been edited to correct typos, spelling errors and to improve grammar...

"All that is gold does not glitter..."

Indiana is NOT known for Obsidian at all! Obsidian is produced when felsic lava extruded from a volcano cools rapidly through the glass transition temperature and freezes without sufficient time for crystal growth. There aren't volcanoes in Indiana (not for hundreds of millions, even billions, of years -- most surface rocks in Indiana are sedimentary)
No you aren't.
Slag glass can and will have varying colors in it, I don't know where you got the idea that slag won't have varying colors. I have 40 lbs of slag glass that I cut cabs and polish and most have milky or varying colors.
I can say it is NOT Obsidian. Obsidian does NOT come in a light or transparent green color. I welcome anyone to show me documentation of a light green, transparent Obsidian. Though obsidian is dark in color similar to mafic rocks such as basalt, obsidian's composition is extremely felsic. Obsidian consists mainly of SiO2. In some Obsidian, the inclusion of small, white, radially clustered crystals of cristobalite in the black glass produce a blotchy or snowflake pattern, hence the name "Snowflake Obsidian" Other colors of Obsidian are, mahogany, red, flame, midnight lace, jet black, pumpkin, brown, gold sheen, silver sheen Obsidian. There is also an Obsidian called Apache Tears which is only found in Arizona and New Mexico.
So, there has never been a color of Obsidian known or documented that has the color that you have found. Obsidian is a hardness on the Mohs scale of 5 to 5.5.
Cabin fever, I read the link you put here. It doesn't say one word about Obsidian.
Naturelover, can you post a picture of the "blue Obsidian"? I really want to see some of that....
Apatite is a 5-5.5 on the Mohs, just like slag glass. Larimar is not transparent!
Here is some of the slag I have and the last pic. is some that I have polished. It sure doesn't look to me like it has "varying colors....

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Here are a few of the rocks I have done....

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Earthdog, those are absolutely beautiful!!!! How did you get them shaped like that?? And so smooth and shiney?? Just tumbled??
I would love to make some up......I can see painting on them.....ohhhhhhh so nice


Alice in Virginia

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What about Rainbow Obsidian? Though that may just be another term for one already mentioned.

Love the rocks and glass!!! Wish I could get some nice slag.

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Nevermore

Kristie - go get several expert opinions on your specimen and don't pay any attention to what us amateurs have to say. This is the wrong forum for garnering the correct mineralogical information about your find.

Earthdog, it's really nice to see that I'm not the only rock-hound on this board. I looked at the pictures you posted, also I saw some of the other pictures you posted earlier this year of the botswana agates, you have some exquisite and well selected specimens there. Well done with the tumbling you've done with your stones. Botswana is one of my favorite stones to work with, it is such a physically soothing and spiritually enhancing stone for most people.

Regarding the pics you posted of the slag glass, it's beautiful but it all looks like ordinary slag glass to me, all sharp corners and brittle razor edges, no humps or rounded curves to it like you would find with nature-smoothed obsidian or limb-cast, and very distinct and finely deliniated color variations - no blending of colors and opalescence to your slag, that's for sure. Very beautiful slag for cabbing and making jewellery for anyone who's interested in costume jewellery. Kind of reminds me a bit of the Venetian Glass beads that were so popular during the 30's - 60's.

I don't know if GoddessKristie's stone is obsidian or limb-cast or slag glass because all we have here is pictures of it. If I had it in front of me and could examine it with my own equipment I would be better able to tell if it was slag glass or some other. I'd test it for fluorescense and hardness for sure. The pictures of it looks to me like either obsidian or opalized limb-cast, it doesn't look at all to me like slag glass. I've never yet seen slag glass that is as clear and blended in coloring as her specimen. I think that the only way she will know if she has slag or obsidian or whatever is by having it looked at by a professional mineralogist / geologist and getting 2 or 3 professional opinions from experts. Not like you an me, eh? - we're both obviously just amateurs in our respective hobbies compared to some of the professional mineralogists and geologists out there.

With regard to your request for photos of my obsidians the answer is "I don't think so" to that. I have to find them in all the boxes they're packed in since I just moved. Maybe I'll send photos to Kristie if I can find the right box but I don't feel like posting them here just because you demand them. I have what I have and I know where they came from and what they're good for so I'm content with that, that's all that's important to me and my clients. I've only expressed my opinions of Kristie's specimen based on her photos and on what I've seen and collected over the past 50 years and I'm not trying to prove any point, it's really not that important to me if her specimen is slag or obsidian or opal or whatever, it's her back yard, not mine or yours. Personally, I hope she's sitting on a fortune's worth of some new mineral such as the many never-before-seen new minerals that have been popping up all over the world in the past 20 years.

OK I have been doing some research to find out about how Obsidian could have come from to end up in Indiana and I'm sure I have found the answer.

Now just remember I'm not asserting what the rock is that this thread is about only offering an answer as to how it ended up in Indiana.

http://web.mac.com/elleryfrahm/iWeb/...AF7E52528.html

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OK, another rock geek here! (although not as much as I used to be, since we are moving out of the rock & mineral business...) For probably 12 years now my husband and I have supplemented our income very well by selling at rock & gem shows. We have primarily done this by buying up inventories from defunct old-time roadside rock shops and taking them on the road to shows. A traveling rock shop, we sometimes called it. A LOT of the stuff we bought for resale we had to clean up, identify, and repackage in order to sell it. In fact, most of it. So I got really pretty good at mineral and rock ID-ing. Pretty near every show we did we had at least one person bring in something special to have us look at it and tell them what is was. It was a blast! Since my DH is an archeologist and flint knapper, working primarily in obsidian, we also heard a LOT of stories about finding arrowheads, and different peoples theories about artifacts and obsidian in general. A lot of folks just like to visit and talk.

So here is my opinion, worth only what any opinion is worth. When I looked at the pic of the OP's specimen, I saw first color. Not much is that color in the rock world, so that limits it. I then noticed a little what looked like opalescence, I thought "opalized something?" for about 1/2 a second, and then my brain said, "oh that's that glass from the factories around Steubenville Ohio." (I guess my brain wanted to get really persnickety about a possible source location;-) Now I'm just talking from my own experience here, and it IS almost impossible to see everything in a photo on a computer screen, but from what the piece looks like and the fact that the OP says there were glass factories around there, I am pretty confident in my identification, man- made glass. Sure is pretty though.

FWIW, I have never seen obsidian that color, and I have a pretty broad exposure to it. Obsidian is volcanic glass, it occurs in areas of volcanic activity, and it was traded across to other areas by prehistoric peoples. Some is fine and almost transparent, like glass, and some has more mineral in it making it darker and more opaque. Most of what I've seen out here in the West has been dark, shades of smoke to black, some is reddish or brownish too. When you hear about a blue sheen, a green sheen, a gold or silver sheen, or rainbow obsidian, what it looks like is a really fine pulverized shiny or almost metallic coating on a dark stone when the light hits it just right. As you rotate the piece in the sun, it looks almost like a bit of gas spread out on the surface of water in the driveway. That much color, not a solid chunk.

Thanks for the discussion, hope this helps.

Here are pictures of Obsidian.

Blue

http://www.thegemtree.com/images/med...AN%202_MED.jpg

http://www.thegemtree.com/images/ori...%20nuggets.JPG



Green

http://www.indostone.com/images/Green_Obsidian.jpg
http://topgems.homestead.com/GREEN-OBSIDIAN-SM.jpg

Blue/green

http://crystalclearemotions.com/bluegr~1.jpg

Blueish black

http://www.littlegemsrockshop.co.uk/...og/OBSSH01.JPG

Black/white specks

http://www.whimsical-wishes.com/imag...keObsidian.JPG

MohObsidian

http://www.banjo-creek.com/Images/Ro...sidian4.5c.jpg

Black

http://www.prcupcc.org/stones/images/mr/obsidian.jpg

Now what I can find out about the blue and blue green is that they are made into jewelry and not much can be bought in the raw but you can find a few pieces out there.

Hillbillybob

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Kristie - When I get home from work tonight I'll try to find the box I've got my biggest obsidians packed into - I'll specifically look for the blue piece I collected from the Nass Valley in northern BC. It's color is very similar to these 2 pieces of obsidian I found on internet (see links below), but mine is quite a bit lighter in shade, very clear and it has a delicate opalescent pearl sheen on it but I don't know if the pearl sheen will show in the photo. But I'll give it a shot and see how it comes out. If I can get a good enough photo of it I'll pm it to you (and yes, I'll post it here on this topic too).

http://pietre.dinoweb.net/tool/class...5720.jpg&h=151

http://www.gemcutter.com/gems/m/m576.jpg

The rest of the obsidians are all wrapped in paper and packed away with other stones in boxes so I won't try finding them. Too much of chore to find them amidst all my other boxes of possessions since I've just moved and nothing has been unpacked yet.
.

naturelover,
Please explain to me how that question is demanding.
I'm sorry if I hurt your feelings in anyway with ASKING for you to post a photo of the "blue" Obsidian. Anyone reading this thread can clearly see that I didn't demand you to post a photo. But have it your way.
You still want to tell me that even the 2nd and 3rd pictures I posted of the slag doesn't have any varing color? It looks to me as if it could be opalescence,: having a milky iridescence.
I will agree my slag is sharp on the edges because it is fresh slag, maybe a year old at the most and has not been sitting under 2 feet of dirt for many years.
Also your statement,
Is also not true. Quite often Tourmaline is found in chunks and also Aquamarine but not as often as Tourmaline.
Here are a few photos from some mines in San Diego County.




Aquamarine,

Oh BTW, I have been doing Lapidary for close to 30 years now, part owner and manager of a rock shop for the last 9 years when I am not working my other job. I go all over the country digging and visit at least 3 mines a year studying rocks and minerals. I consider myself a bit more than an amature so please speak for yourself with this quote from you,
Again, naturelover I am sorry if you feel I questioned your integrity.

Hillbillybob, I read that website you posted a link to, and quote,
Even Ellery Frahm, a doctoral candidate for Archaeology states Obsidian is not native to Indiana.
The links you also posted for the pictures, I would bet all my rocks and my rock shop that the first two links are NOT Obsidian. Anyone can throw a name on any rock or mineral they want, just like "blue Obsidian", or "Graveyard point" plume agate or "Ocean Jasper" like my friend Gene Mueller (owns the Gem Shop)and Paul Obenich that discovered Ocean Jasper. Like I asked in my other post, I welcome anyone to show me documentation of a light green, transparent Obsidian, or light blue Obsidian for that matter.
Any Obsidian can be transparent if you cut it thin enough, even the Mahogany Obsidian.
On a regular basis I tumble Apache Tears for customer and 3/4 of them turn out transparent, if held up to light.

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Look you missed my whole point of my post and that is that Native Americans traded Obsidian among themselves and it could have come to Indiana that way. I never hid or tried to hide anything with my link.

I think you missed my whole point in posting how Obsidian could be and have been found in Indiana.

Hillbillybob

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By Jim Miller, B.Sc., M.Sc. Geology*
The ancient volcanic hills called Glass Buttes hold a dazzling variety of gem-quality obsidian, including: mahogany, red, flame, midnight lace, jet black, pumpkin, brown, rainbow, gold sheen, silver sheen, green, lizard skin, snowflake and more.
http://volcano.und.edu/vwdocs/vw_hyp.../obsidian.html

No sir, Mr Hillbillybob, I didn't miss your point. I was in agreement with you for what
Kathy in MD said about Obsidian being one of Indiana's natural gemstones.
I don't think I ever implied you were hiding anything in your link!
Appway, I do believe there is some green Obsidian but not the light, transparent green that was stated elsewhere in this thread.

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Yeah have not found any light transparent green either
But will keep looking
By the way your fotos are beautiful and would love some of your polished stones

heres one thats close
http://www.picsearch.com/info.cgi?q=...wiqb4&start=41

Well, being a professional lapidary on and off for 30 some years, I thought I would come out of lurker mode on this post. First I'll say that I will not claim to know every thing.

My immediate thoughts on the pictures is that it is some very nicely colored glass. Given where she found it and there is not any more there from what I remember reading, is it not possible it is an old colored glass bottle or statue that has been under the lawn mower or around the tiller tines many times. Just my thought.

To answer another question, I have read where it takes 100 years for the earth to build one inch of soil on average.

GoddessKristie, I recommend you post your pictures at either mindat.org forum
or rockhounds.com forum to get your answer. Many knowledgeable people on both, probably some local to you.

I would think that a clue would have been in the reaction that the Lapidary/Rockhound/etc she took it to had. IF it were a rare specimen he/she (we must be PC here) probably would have wanted to buy it, know exactly where it was from, etc. If he/she showed no major reaction you can pretty well bet that it is probably what they said it was. I doubt most rock hounds get very excited about slag glass. That said be wary of strangers digging in your garden.

That green obsidian you have a link to above looks more like malachite to me, but I'm not even an beginner in rocks and minerals...

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Malachite is more of a brighter green that that link shows. I can take a couple pictures of the malachite I have if you want...

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