What are these shiny black rocks?

[wildcatman71]

Last week we went to the Cave in Rock, IL area and was digging around in an old fluorspar mine....and found these. These are the only ones like this I have ever found there. Very shiny, glassy black rocks. Please let me know what I have here. Thanks!!

 

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[Tuberale]

HPD answers Tuberale's answers: (Please, don't let us bore you. Not everyone could be iterested in this discourse.)
1. That is not an answer.
It IS an answer. Most obsidian is black for the same reason. Rock that is molten becomes predominantly black.

2. I, too, have a Canyon Diablo, although it is an individual with full crust, not a piece. (Canyon Diablo is the Arizona Meteor Crater) Do they have meteor usage right? I can't argue terminology. And they have drilled quite deeply into the bottom of the crater to mine the iron, without finding any. Puzzling. My question is, why are craters round when most meteors or meteorites come in on a very shallow angle? Shouldn't they be oblong?
Mine has no fusion crust. It does have a lot of rust though.

It should be Meteorite Crater. Meteor is an object still in the air.

Actually, there IS a mass under the crater. But deep. Probably too deep (and too large) to remove. Besides, so many smaller pieces from around it that finding the main mass is less important. Consider Sikohte-Alin from Siberia: tons of material found after it broke up in the high atmosphere. But covering a massive strew field. Some of the pieces buried themselves some 15-25 feet deep. But the pieces didn't form noticeable craters.
3. There are lava flows all over So. Colo and N. New Mex with the columnar "crystals" of basalt. Cool stuff because you know what you are looking at when you see it.

6. Mea culpa on the pua pua.. but there is a name for the ropy lava flows. But I rest my rep on the Aa. You go walk barefoot on an Aa flow and not say "ah...ah....ah....damn." and prove me wrong. That shows that at least one vulcanologist had a sense of humor, or perhaps none at all when he made a midnight run for the potty.
Interesting theory, but wrong. The Hawai'ian language uses many double vowels, both of which are sounded. And A'a is definately Hawai'ian. But because Hawai'i is a chain of islands completely volcanic in origin, the language also has many words for lava. Kind of similar to the Aleutians having many words for snow.

8. We pretty much agree except that all lava bombs are ejecta but not all eject form as lava bombs. But is a non-bomb form of ejecta hits you, ouch!
Not necessarily. Most of the ejecta that hit people all over the world didn't hurt at all. It's called ash or rock ash. Bad stuff to breathe, though.

I am back to offering photos of tektites, both Asian and Czech. Just in case anyone is still bored and still reading this. How did we get on volcanos, anyway?

I would love to see pumice flows (the only pumice I have in my collection came in the pocket of my stone washed jeans) and obsidian flows. The only obsidian mass I have seen is the cliff in Yellowstone. And we dug a big chunk out of the side of the road up to the top of the big cone No. of Santa Fe. The really big one with a ring road around on the top of the crater.

The only pumice flow I know of is next to Lava Lake in Central Oregon. As a child I went there with my parents. We thought it great fun to toss a piece of rock from the edge of the lake and watch it float for a long time.

 

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[Arid-Zone-A-seeker]

Volcanic glass, Obsidian, comes in many different forms, from the size o the pieces I would bet it is rail bed ballast.
What kind of quarry is it?

 

[yzrowell]

It looks like Tourmaline

 

[rock]

With the bubbles showing in them I would go with slag. Although I dont know of any others with bubbles. Did your MD pick them up? Slag sometimes is detected as metal on your MD.

 

[Turkısh Man]

Black obsıdıan hardnes-5-5.5



Black agat hardnes-7



Black tourmalıne hardnes-7-7.5




Anthracite hardnes-3-3.5

 

[Eu_citzen]

I'll answer some questions best I can/know. Simply because it fascinates me.

1. If tektites are ejecta from meteorite hits, why are they all (pretty much) te same color, whether the met. hit granite, red sandstone or white limestone? And if the met. explodes in the
atmosphere, how can they create molten ejecta, even with small pieces.

Quite simple, the high speed that they travel at give an impact a mighty force.
Just look at the impact in Russia which created diamond when it hit a graphite rich rock.

The reason that they look much the same is due to meteorites often hitting soil rather then solid rock. Much soil consists of, among other quartz, K Feldspar and mica. I guess that might be the cause or at least a reason why they look much the same.

2. Show me a Canyon Diablo Tektite. Really. I would like to see one.

Not familiar with that site. But perhaps it's so old that most tectites have eroded away.

3. Obsidian is rapidly cooled lava that did not develop crystal structure. But that also is the part that I don't have a full understand of.

Correct, the crystal grows as long as age, space (room to grow in) and material ("building blocks") exist.

 

[rock]

I did see some brown in his rocks which does look like mahogony obsidian. But does obsidian have bubbles in it? I dont have any of that type around here to compare it with. And just in case I missed it.......what is his type of rock?

 

[Britt82]

Last week we went to the Cave in Rock, IL area and was digging around in an old fluorspar mine....and found these. These are the only ones like this I have ever found there. Very shiny, glassy black rocks. Please let me know what I have here. Thanks!!

I believe they are exogenic fulgurite. I found the SAME exact specimens all over a sand deposit that is filled with fulgurite. And I mean identical... if youre interesred in pics lemme know

 

[a2jones]

looks more like tektites,obsidean chunks usually have some sharp edges.

 

[Ponchosportal]

Slag

 

[IAMZIM]

now I am really confused....it looks just like the obsidian....as well as the anthracit coal.

Anthracite coal can have a glassy appearance as does obsidian, however obsidian is MUCH harder. Try a hardness test!

 

[Ponchosportal]

As I said ...... to me it is obviously SLAG (bubbles, lineation's, glassy appearance, hardness in excess of 6.5).

Take your materials to a local rock and mineralogy club and they will be happy to tell you what you have found.

There is no reason to be confused further at this point. Take it to a local club!

Please report back to us what the club tells you.

 

[stdenis_jd]

you guys realize this post is over 8yrs old right?

 

[IAMZIM]

you guys realize this post is over 8yrs old right?

I do now....lol!

 

[joeboken]

I'd say it's Black Tourmaline.

 

[JTJones]

It looks like old slag glass.....kind of weathered.....there are a lot of air bubbles trapped in the glass.....I have a smelter and I am willing to bet it is old slag.....the bubbles in obsidian would appear more consistent in size ......not sporadic sized bubbles as seen in the photo....
here is a photo of my slag glass....sorry don't have more of a close up...

db

Was metal detecting in my back yard and I found where there is a ton of this. I've found some older artifacts around that area and there's a foundation sort of like there may have been a barn or something there. Perhaps someone was smelting?

 

[Charon_Sin]

Last week we went to the Cave in Rock, IL area and was digging around in an old fluorspar mine....and found these. These are the only ones like this I have ever found there. Very shiny, glassy black rocks. Please let me know what I have here. Thanks!!

That is Gilsonite

 

[Lygore]

I vote slag glass. Especially if it is heavy with a bunch of bubbles in it. You could try to see if a strong magnet sticks to it, as they sometimes do. Typical slag glass also sets off a metal detector if you sweep it over the sample.

 

[vibetransference]

May I offer an alternative? May still be glass, though. Just not obsidian in the classic sense.

A meteorite which strikes the Earth produces ejecta from th

Last week we went to the Cave in Rock, IL area and was digging around in an old fluorspar mine....and found these. These are the only ones like this I have ever found there. Very shiny, glassy black rocks. Please let me know what I have here. Thanks!!

Hi guys, in case you were not aware.. there is a town called Hicks
e impact site, which can melt from the pressure of the impact, but solidify while still in the air. Usually dark, glossy black, similar to obsidian. Called tektites. Try searching for images on google for tektites.

 

[vibetransference]

Hey all. In case you were not aware, there's a town in Illinois near Cave in Rock called Hicks. There in is a spot in Hicks called Hicks dome. That is an impact crater that turned almost volcanic in that area. There in, (and surrounding areas) exists Obsidian (both black and green) tektites and volcanic glass. The very best way for you to tell if you have obsidian is, does it have little to no air bubbles and does it break like glass. Glass brakes in a curved structure and you can almost always cut yourself or anything else with it. Tech types and volcanic glass are going to be a little more brittle than obsidian the other way you can find out if you have obsidian or not is of course the heat method. With that said, obsidian still is glass so it's going to melt like glass so it's going to take a lot of heat. Hope that helps. I'm from Southern Illinois and I've visited both cave and rock and Hicks Dome and I found all three materials