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What rock is this?
  
  Index -> FOR BEGINNERS: What is it? Where is it from?
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Roxana Roxy




Joined: 19 Sep 2019
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PostPosted: Sep 19, 2019 06:12    Post subject: What rock is this?  

Someone can give me an opinion? It looks black but is dark green. It glows, and has little yellow crystals. It's like glass, and I found it in Italy, during a walk in the mountains. Seem's like obsidian.


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Carles Millan
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PostPosted: Sep 19, 2019 07:09    Post subject: Re: What rock is this?  

We understand your desire to know what your samples are, but it is too difficult to determine this from photos. If you have a rock shop nearby, or a lapidary club, we would suggest you go there to ask. In case for some reason you can't join a club then you can also try this other web page: https://www.reddit.com/r/whatsthisrock . You can also read Asking: What is it? - Where is it from? and provide us with some basic information about the specimen.

We want to help those who are truly curious, but you need to give us more information before we can help you. Sorry to be so strict but we receive too many queries from people asking more or less similar questions and finally we have been a little bit saturated by those kind of requests without no more information than the images.

Thanks for understanding
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Josele




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PostPosted: Sep 19, 2019 10:15    Post subject: Re: What rock is this?  

To me, it looks like slag glass.
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Roger Warin




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PostPosted: Sep 19, 2019 10:24    Post subject: Re: What rock is this?  

obsidian
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Carles Millan
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PostPosted: Sep 19, 2019 10:33    Post subject: Re: What rock is this?  

As Gail Spann recently said I am more motivated by a question, asking for a favor, to end with PLEASE. Perhaps you would have gotten more answers.
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lluis




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PostPosted: Sep 19, 2019 10:35    Post subject: Re: What rock is this?  

I agree with Josele...

It looks like what when a child I thought was obsidian, found in an open work in the streets of Barcelona (exactly, Major de Gràcia, between Montseny and Pere Serafí... For the ones that wish detail...)
Later I realized it was just a piece of glass slag, man made and left there by who knows when and by whom....

With best wishes

Lluís

P.D.: although, after have been seen some chunks of green glass labeled as "green obsidian" (some years ago; now, no, thanks God!), I begin to think about what people wish to say when they say "obsidian" :-(
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Josele




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PostPosted: Sep 20, 2019 04:08    Post subject: Re: What rock is this?  

My humble opinion is based on the fact that I don't know of volcanic deposits near Como. But maybe they exist...
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lluis




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PostPosted: Sep 20, 2019 09:08    Post subject: Re: What rock is this?  

In my case, is just for aspect.
The poster never said that the piece is from Como.... (and again, with no info, answers will be as limited as the info given...)

Besides, obsidian is known in some places. Glass slag and melting slags, both resembling obsidian, are known from many more places. Such as the big piece found in Barcelona.. (we are in the Fire Belt, but there was never a volcano near Barcelona (well, many in Olot, but that is not exactly "near"))

With best wishes

Lluís
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Pete Modreski
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Joined: 30 Jul 2007
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PostPosted: Sep 20, 2019 10:11    Post subject: Re: What rock is this?  

Roxana (and Forum friends),
Indeed, it looks like obsidian, and as is being discussed, glassy slag can look very similar. And in fact, as most of us know, there are not really any easy tests (especially that a "beginner interested in rocks" could do) to tell them apart. Recognizing which it is, is mostly a matter of visual appearance, and that just takes "experience".

And as has been said, one best guide to which it is, is where it was found--knowing whether this is an area where there are volcanic rocks, or not. So (more advice to Roxana), this points out the reason for some of the guidelines given in our instructions to posters--which, as has been said, anyone posting REALLY needs to read, especially when trying to ask questions about a specimen you have found--that, if you're posting a picture of something and asking about it, it's very important to clearly say WHERE it's from (as much as you know about that).

We observed that your identity on the Forum gave your location as Como, and accordingly, most of us assumed that meant that you, and this glassy rock, were from Como, Italy, but that may or may not have been quite correct. As a matter of fact--I live in Colorado, USA, and there is a small but well-known locally town of Como in the Colorado mountains, and a first thought for me was, "Which Como is she from?".

And also--we can't much expect a "beginner" to necessarily know if the area where they found something is, in this example, commonly a source of volcanic rocks or not. Depending on the type of experience of each of us, for some areas it will be very obvious that there are or are not volcanic rocks there, but for other areas, it may take a lot of specific local knowledge to know that.

As a final few words--as you (Roxana) may have realized from the exchange of messages here, this Forum is an exchange of messages and discussion among "friends" who have common interests; we try to be not only polite, but friendly and open with information about ourselves and the people we are writing to. So, it's kind of appropriate, for a new member, perhaps posting a question for the first time, to say a few words of welcome and introduction, explain who you are, where you are from, and something about what your level of experience and what your special interests (if any) are, regarding minerals. I realize that some other online forums are not like this--they tend to be more "anonymous", with brief, to-the-point questions and short answers, not much personal talk. This Forum is not like that--which one may get a clue about, from the first word in its title---this is the FRIENDS of Minerals Forum!

Best regards,
Pete Modreski, Denver CO
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Riccardo Modanesi




Joined: 07 Nov 2011
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PostPosted: Sep 20, 2019 11:48    Post subject: Re: What rock is this?  

Hi to everybody!
It depends on WHERE you found it. In Sicily, for example, it's not so seldom to find it, especially in the island Lipari and near the Etna volcano. I feel like excluding Northern Italy and the Alps.
Greetings from Italy by Riccardo.
Roxana Roxy wrote:
Someone can give me an opinion? It looks black but is dark green. It glows, and has little yellow crystals. It's like glass, and I found it in Italy, during a walk in the mountains. Seem's like obsidian.

_________________
Hi! I'm a collector of minerals since 1973 and a gemmologist. On Summer I always visit mines and quarries all over Europe looking for minerals! Ok, there is time to tell you much much more! Greetings from Italy by Riccardo.
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