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Author Topic: Rocks Rocks Rocks !!...But What is Rock ?  (Read 22494 times)

Offline Sarah Elizabeth

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Rocks Rocks Rocks !!...But What is Rock ?
« Reply #25 on: 17/12/2007 15:25:58 »
i really love rocks and geology is my favourtie subject next to geography !!some sedimentary rocks are basically the broken up and weathered remains of  igneous and metamorphic rocks. other sedimentary rocks have been formed simply from layers adding ontop of one another, and sedimentation occuring to make them rock-like haha . Igneous rocks are volcanic and made in very high pressure and high temperature environments where as Metamorphic rocks were once sedimentary ( and in rare cases igneous) and theyve been heated intensely and had alot of pressure put on them to recreate rocks of a metamorphic composition... my favourites, Gneiss and Schist... god you have to love them :P 
 

Offline Karen W.

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Rocks Rocks Rocks !!...But What is Rock ?
« Reply #26 on: 19/12/2007 22:38:25 »
OK here are some rocks what can you tell me about them.. I found them today on my walk..What kind are they?








 



« Last Edit: 19/12/2007 22:44:14 by Karen W. »
 

Offline Bass

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Rocks Rocks Rocks !!...But What is Rock ?
« Reply #27 on: 19/12/2007 23:45:35 »
Hi Karen
I particularly like the green rock.  Can you tell me any more about it?  Can you scratch it with a knife?  Does it feel smooth, or rough?  Can you see any crystals in it?
The larger piece has some obvious veins in it, I would guess quartz.  Also some iron staining.
The small dark red rock is probably jasper.
With the possible exception of green rock, they are probably all sedimentary- although they've probably all been altered (or changed) since deposition.  It appears that all these rocks may have been silicified (silica added), making the rocks harder.
 

Offline Karen W.

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Rocks Rocks Rocks !!...But What is Rock ?
« Reply #28 on: 20/12/2007 00:55:58 »
Nope can't scratch it with a knife Smooth on one side and has some texture on the other side. It has some teeny tiny holes on the smoother side harly visible like you might have seen if it were to boil. needle size tiny needle.

No crystals that I can see but it is super hard and pretty green.. me favorite color!

The big rock the picture is deceiving.. It is not that color It is burgandy around the bottom with whit splashes On the top there is a large white section on the back..





 

Offline Bass

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Rocks Rocks Rocks !!...But What is Rock ?
« Reply #29 on: 20/12/2007 04:42:57 »
larger rock may be volcanic?  Hard to tell from the picture.
 

Offline Karen W.

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Rocks Rocks Rocks !!...But What is Rock ?
« Reply #30 on: 20/12/2007 06:15:13 »
Oh dear that middle picture is so blurry..Sorry.. aai will try tomorrow to get a better one. Thanks bass.

What did you think the green one was?
 

Offline Bass

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Rocks Rocks Rocks !!...But What is Rock ?
« Reply #31 on: 20/12/2007 17:57:18 »
The color is close to fosterite (ultramafic mineral), but my guess would be diopside/augite (mafic minerals).  Minerals can be divided into two end spectrums- mafic and silicic.  Mafic minerals tend to be iron, magnesium and calcium rich.  In general, ultramafic and mafic minerals come from the mantle, silicic minerals from the continental crust.  Fosterite, diopside and augite would form as metamorphic minerals from mafic igneous rocks, which is reasonable for your location.
 

Offline neilep

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Rocks Rocks Rocks !!...But What is Rock ?
« Reply #32 on: 20/12/2007 19:01:35 »
I know all about Rocks !

Here is is my expert evaluation of Karens Rocks.





Glad I could help.
 

Offline Karen W.

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Rocks Rocks Rocks !!...But What is Rock ?
« Reply #33 on: 20/12/2007 21:10:32 »
WOW.. YOU are amazing...What Knowledge lies in that Brain of yours!!! HEE HEE HEE! LOL..Thanks for the Info!
 

Offline Karen W.

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Rocks Rocks Rocks !!...But What is Rock ?
« Reply #34 on: 20/12/2007 21:16:49 »
The color is close to fosterite (ultramafic mineral), but my guess would be diopside/augite (mafic minerals).  Minerals can be divided into two end spectrums- mafic and silicic.  Mafic minerals tend to be iron, magnesium and calcium rich.  In general, ultramafic and mafic minerals come from the mantle, silicic minerals from the continental crust.  Fosterite, diopside and augite would form as metamorphic minerals from mafic igneous rocks, which is reasonable for your location.

The green one is very beautiful. Do you think it could be cut into a heart shape And polished?? I could not even scratch it with a knife.. I love the color and would also like to make a necklace out of it!

What about the red one? Do you think it could be made into a single stud earring?
It really is not orangy red? Sorry Neily it is quite brite red...! My camera does not seem to be doing a good job with closeups or the color.. LOL! Really, it is the photograper! LOL..!! Me is not good with a camera! LOL~!
 

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Rocks Rocks Rocks !!...But What is Rock ?
« Reply #34 on: 20/12/2007 21:16:49 »

 

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