rollingstone
starting to spend too much on rocks
Member since July 2009
Posts: 236
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Post by rollingstone on Feb 15, 2005 17:32:55 GMT -5
Anyone up for some rock ID? This is a rock I found in a river and thought was something like granite, but now I'm not so sure. It scratches glass easily, but won't scratch quartz or feldspar. It can be scratched by quartz, but not by feldspar. So it looks like Mohs 6 to me. Isn't granite mohs 7? Kind of looks like cheap spiderman jasper but not hard enough. Kind of looks like rhodonite, but much too red. Maybe it is feldspar, but then what's up with the black veins? It could be either metamorphic or igneous. Ideas? Dry:  Wet:  |
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Post by krazydiamond on Feb 15, 2005 17:39:01 GMT -5
yer right, looks like granite..except for the veins. interesting.
KD
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Post by Cher on Feb 15, 2005 18:08:08 GMT -5
I find a lot of stuff like that here, with the veins too. Imagine the force it took to crack that stuff. Don't think it's granite thought, isn't granite more "granular"? Here's a link to a page that has a picture of granite on it. Common Rocks and Minerals You'll have to scroll down some but it's a good pic of it. Cher |
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Post by docone31 on Feb 15, 2005 19:58:23 GMT -5
It looks like red granite. Granite has definate veins on a lot of pieces. Should polish real easily.
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MichiganRocks
starting to spend too much on rocks
"I wasn't born to follow."
Member since April 2007
Posts: 154
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Post by MichiganRocks on Feb 16, 2005 7:44:14 GMT -5
I don't believe it's Granite. Rock must have a minimum of 20% Quartz to be Granite and I don't see that in your picture. Looks more like Syenite to me. Syenite looks similar to Granite except that it has less than 5% Quartz. The pink color would come from the high percentage of Pink Orthoclase in the rock. Syenite also is commonly found with with black lines in it giving it the appearance of "flow". Lastly, Syenite is also softer than Granite with a Mohs of 5.5 - 6.
Ron
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Post by creativeminded on Feb 16, 2005 9:12:54 GMT -5
It also looks like Rhodonite. I have some chip beads that I use.
Tami
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rollingstone
starting to spend too much on rocks
Member since July 2009
Posts: 236
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Post by rollingstone on Feb 17, 2005 2:19:29 GMT -5
Thanks for the opinions. I'm perhaps most taken with the syenite option. Several options to investigate further at any rate.
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Glenn
having dreams about rocks
Member since January 2005
Posts: 55
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Post by Glenn on Feb 17, 2005 20:25:36 GMT -5
I'd call that Granite ? We have that type in north Montana the size basket balls the glacier rolled threw .I have always thought it was granite from Canada ! Glenn  |
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MichiganRocks
starting to spend too much on rocks
"I wasn't born to follow."
Member since April 2007
Posts: 154
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Post by MichiganRocks on Feb 18, 2005 13:27:51 GMT -5
This picture is a classic example of Rhodonite as it's normally found in glacial or river rock. I just took this one out of my tumbler today and was one that I picked up locally. Ron  |
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Post by krazydiamond on Feb 18, 2005 15:48:06 GMT -5
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MichiganRocks
starting to spend too much on rocks
"I wasn't born to follow."
Member since April 2007
Posts: 154
|
Post by MichiganRocks on Feb 18, 2005 18:55:52 GMT -5
Rhodonite is a mineral, not a rock. It is usually colored anywhere from pink to dark red and in it's pure state forms a square crystal. In your rock, the pink is the Rhodonite with impurities and the black is matrix. In my rock, it's only the red crystals that are Rhodonite. They were large square crystals before I polished them smooth.
Ron
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