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Author Topic: Not obsidian!?!  (Read 2933 times)

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crustygem

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Not obsidian!?!
« on: January 25, 2018, 04:26:08 PM »

Ok so here is a beautiful black....something! It was the only one like this on the beach or at tide line. When I first saw it I thought obsidian, as it was wet and shiny, score! Would have been my first. However, when I got home and it had dried off it's obviously NOT obsidian. I thought maybe jet? I did gravity test, and again my scale is older and maybe not so accurate, and got 1.97
Steel will not scratch, diamond will.
It has a greenish streak I tried to get a good pic of. I love it!!

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55fossil

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Re: Not obsidian!?!
« Reply #1 on: January 25, 2018, 04:47:31 PM »

   Is it green under all that black skin?????   Trying to see if it is mafic or a basalt type material?
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crustygem

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Re: Not obsidian!?!
« Reply #2 on: January 25, 2018, 04:49:05 PM »

   Is it green under all that black skin?????   Trying to see if it is mafic or a basalt type material?
Well, when I scrape it it is still black

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crustygem

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Re: Not obsidian!?!
« Reply #3 on: January 25, 2018, 04:52:35 PM »

   Is it green under all that black skin?????   Trying to see if it is mafic or a basalt type material?
Well, when I scrape it it is still black

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Check out fracture lines

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lapidaryrough

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Re: Not obsidian!?!
« Reply #4 on: January 25, 2018, 05:59:08 PM »

Hematite  is 97.5% Si;ica & 2.5% Iron. Alaska's Sate rock.
 Botrydole formations. nice material. 
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Silicate life form

crustygem

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Re: Not obsidian!?!
« Reply #5 on: January 25, 2018, 07:32:29 PM »

Hematite  is 97.5% Si;ica & 2.5% Iron. Alaska's Sate rock.
 Botrydole formations. nice material.
I don't think it's hematite. It's specific gravity is way too low. Also I think it's hardness is more than hematite

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crustygem

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Re: Not obsidian!?!
« Reply #6 on: January 25, 2018, 07:32:53 PM »

Hematite  is 97.5% Si;ica & 2.5% Iron. Alaska's Sate rock.
 Botrydole formations. nice material.
I don't think it's hematite. It's specific gravity is way too low. Also I think it's hardness is more than hematite

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This is the pic I have for hematite

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crustygem

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Re: Not obsidian!?!
« Reply #7 on: January 25, 2018, 07:33:34 PM »

Hematite  is 97.5% Si;ica & 2.5% Iron. Alaska's Sate rock.
 Botrydole formations. nice material.
I don't think it's hematite. It's specific gravity is way too low. Also I think it's hardness is more than hematite

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This is the pic I have for hematite

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Also it's not magnetic.

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Phishisgroovin

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Re: Not obsidian!?!
« Reply #8 on: January 25, 2018, 08:15:15 PM »

magnatite i bet

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Slabbercabber

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Re: Not obsidian!?!
« Reply #9 on: January 26, 2018, 05:06:51 AM »

That seems pretty light but I would still bet on high alumina basalt.
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christos

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Re: Not obsidian!?!
« Reply #10 on: November 14, 2023, 07:08:51 PM »

looks like iron ore silicate prob as stayed with alum  silate.. i find similiar in red and green tones at an ancient quarry near a riverwhere an ancient volcano flowed. unless the similiarity
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lithicbeads

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Re: Not obsidian!?!
« Reply #11 on: November 15, 2023, 04:41:44 PM »

Any classically trained geologist upon encountering a thoroughly black stone on the beach would say hornfels. Rockhounds never say hornfels.
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christos

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Re: Not obsidian!?!
« Reply #12 on: November 18, 2023, 12:37:28 PM »

Ok so here is a beautiful black....something! It was the only one like this on the beach or at tide line. When I first saw it I thought obsidian, as it was wet and shiny, score! Would have been my first. However, when I got home and it had dried off it's obviously NOT obsidian. I thought maybe jet? I did gravity test, and again my scale is older and maybe not so accurate, and got 1.97
Steel will not scratch, diamond will.
It has a greenish streak I tried to get a good pic of. I love it!!

Sent from my XT1585 using Tapatalk
did you tryanother SG test with a smaller piece?
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ΔΙΑς ΖΕΥς ΕΛ ΛΑς  -
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