June 22-25: Sainte-Marie-aux-Mines:International Mineral & Gem Show
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 Post subject: Small rock and question from Costa Rica
PostPosted: Thu Apr 20, 2017 2:35 pm 
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Greetings to all from Costa Rica
A few years ago I collected this small rock of a beach and since then I wanted to identify what it is, it seems to be some kind of glass or metal. It draws attention to the stripes or striae it has.
Any idea what could be?? Maybe obsidian???


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Last edited by donaldmata on Tue Apr 25, 2017 2:18 pm, edited 1 time in total.
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 Post subject: Re: Small rock and question from Costa Rica
PostPosted: Thu Apr 20, 2017 9:32 pm 
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I moved your post.
It is NOT a forum announcement.


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 Post subject: Re: Small rock and question from Costa Rica
PostPosted: Tue Apr 25, 2017 9:17 am 
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Thanks


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 Post subject: Re: Small rock and question from Costa Rica
PostPosted: Wed Apr 26, 2017 11:23 pm 
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Try the rock identification in the link below:
http://www.minsocam.org/msa/collectors_ ... ck_key.htm


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 Post subject: Re: Small rock and question from Costa Rica
PostPosted: Thu Apr 27, 2017 4:23 am 
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donaldmata wrote:
Greetings to all from Costa Rica
A few years ago I collected this small rock of a beach and since then I wanted to identify what it is, it seems to be some kind of glass or metal. It draws attention to the stripes or striae it has.
Any idea what could be?? Maybe obsidian???


Donald, because of the black color and the striae, I would guess basalt. Volcanic basalt has a tendency towards soft/hard layers and when water worn produces interesting shaped specimens.


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