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Hristian

Can you help me identify this mineral?

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Hello everyone! I have been reading on here for a few days now and i remembered that i found a weird looking rock when i was young and i still have no idea what it is. Can anyone help me identify it? I'm curious.

20190126_173106.jpg

Edited by Hristian

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1 hour ago, Hristian said:

Hello everyone! I have been reading on here for a few days now and i remembered that i found a weird looking rock when i was young and i still have no idea what it is. Can anyone help me identify it? I'm curious.

20190126_173106.jpg

Is it warm to the touch and does it have a pine smell when you rub it? If so, it's some form of tree sap resin. I think old stuff is called amber.

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56 minutes ago, StringJunky said:

Is it warm to the touch and does it have a pine smell when you rub it? If so, it's some form of tree sap resin. I think old stuff is called amber.

No, it.doesn't. It feels like a rock - cold, solid and it doesn't smell like anything i think. And i have this tree sap resin you are talking about and it's not even close to this thing's hardness, that's why i'm curious.

Edited by Hristian

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4 minutes ago, rangerx said:

Carnelian fire agate perhaps?

 

It might be, i couldn't find exactly how hard this agate is but it looks similar. Thank you.

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It's a sedimentary rock derived from clay. Iron oxides will give it the red color, I've had a small green piece in my coat pocket for over a year since I found it.  

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Doesn't look sedimentary to me.

Looks a bit glassy perhaps a bit 'soapy'.

So red chert is a good suggestion.

How does it appear if held up to the light?

Can you see any fine particles, especially through a magnifying glass?

Can you scratch it with glass, a steel nail or knife ?

Are you in a position to estimate density?
Weigh the piece and drop it into water in a graduated vessel an measure the water volume rise.

Divide the weight by the volume (preferably report both)

Is it magnetic (does it affect a compass needle) ?

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Yes, I agree it doesn't look sedimentary, one of the tests is it will spark when a sharp edge is struck like a match stick off of a piece of iron. The site below gives a good description of the characteristics of Chert and its variations such as Jasper. There are some nice images that show texture and color variation.00235-chert-chalk-conchoidal.thumb.jpg.f30836f5081540e933b48294788073fe.jpg1821-hematite-jasper-quartzite-13-cm.jpg.00f931d0f350f977f50e234a85fe5162.jpg

 

http://www.sandatlas.org/chert/

"Jasper is a hematite-bearing variety. Hematite is an iron oxide that is the most widespread source of red color in minerals and rocks. The sample is from the Løkken ophiolite in Norway. It is associated with SEDEX-type magnetite-hematite iron ore formed by hydrothermal activity at the spreading zones of mid-ocean ridges. Width of sample 13 cm."

"It is usually either dull or semivitreous. It may have many colors, depending on the nature of impurities. Most common shades are gray, white, blue, green, yellow, black, and red. White coloration is usually given by carbonate impurities; organic matter or clay gives black color; red, yellow, and brown tones are due to hematite, green variety may contain chlorite or smectite from diagenetically altered volcanic tuffs.

It occurs usually as nodules in carbonate rocks, especially well-known are chalks with chert (flint) nodules in Western Europe. This rock is often bedded – rhythmically interlayered with chalk, shale or in some cases hematite. The latter is known as a banded iron formation (BIF) which is the principal iron ore upon which our society relies.

Chert is in most cases a biogenic rock, it is made of siliceous tests of diatoms, radiolarians, siliceous sponge spicules, etc. Sometimes microscopic fossilized remains of these sea creatures may be preserved in these rocks. Their siliceous tests are not made of quartz initially, but after burial, compaction, and diagenesis, opaline siliceous sediments transform to quartz. Although the material it is made of ultimately came from siliceous tests of marine species, the rock itself is often not deposited in situ. It may move as a silica-rich liquid and form nodules in rocks by replacing the original (usually carbonate) material. So chert is also sometimes said to be a rock of chemogenic origin. Bedded variety seems to be often associated with turbidity currents."

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32 minutes ago, studiot said:

Are you in a position to estimate density?
Weigh the piece and drop it into water in a graduated vessel an measure the water volume rise.

That's what I would do the first.. +1

 

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1 hour ago, arc said:

Yes, I agree it doesn't look sedimentary, one of the tests is it will spark when a sharp edge is struck like a match stick off of a piece of iron. The site below gives a good description of the characteristics of Chert and its variations such as Jasper. There are some nice images that show texture and color variation.

 

 

I should have noted that the Cherts are a sedimentary rocks and some can look like the OP.

It is not rounded enough to be a water tumbled pebble of say agate or jasper, as found on beaches.

I am not sure but I think I can see remnents of a typical obsidian conchoidal fracture in the centre of the OP picture, so the specimen could be a red obsidian, although some forms of chert (as flint) exhibit this fracture mode.

It is also a bit large and pure to be a red feldspar, which is another possibility.

Density and microstructure will tell the difference without destructive testing.

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15 hours ago, studiot said:

 

 

I should have noted that the Cherts are a sedimentary rocks and some can look like the OP.

It is not rounded enough to be a water tumbled pebble of say agate or jasper, as found on beaches.

I am not sure but I think I can see remnents of a typical obsidian conchoidal fracture in the centre of the OP picture, so the specimen could be a red obsidian, although some forms of chert (as flint) exhibit this fracture mode.

It is also a bit large and pure to be a red feldspar, which is another possibility.

Density and microstructure will tell the difference without destructive testing.

It weights around 3 grams and it's very hard. I tried scratching it with another rock, a glass and a steel knife, only the knife barely scratched it. It has something inside of it when i look at it on the light but i don't know what it is, it's a little circle (3 of them to be exact).

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3 grams doesn't sound like much, are you sure?

From the picture I rather expected something approaching 10.

What about the volume?

Possibly a local pharmacist shop might have a suitable measuring cylinder they could help you with.

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These are beautiful pictures of rocks you have, I am very interested in where you found these they may be worth some big bucks!

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