Thanks Roberto & Silvy! It is volcanic rock that had air pockets when it cooled. These pockets filled up with other minerals & gave it the vein of color.
Could you say that in English please??
LOL! Basically from the best of my understanding the hot volcanic rock (basalt) gets air pockets which fill up with minerals and makes the colorful streaks. I spent a good bit of time today trying to make sure I had it right as I am not that great at geology. I remember reading something in the nature center BUT of course I never wrote it down or took a photo. Finally I found an article about the North Shore geology that used this term> I hope I have it right. If not I would think that Peter would give me a heads up.
Nice Amygdules, joyfotos. I've never seen nicer Amygdules. I think I love Amygdules.
Bagpipe Amy dudes? What are you talking about?
LOL! Norrel, it is kind of a cool sounding word isn't it? This was the first time I had heard the word, too.
LOL! LOL! n1w now I will never have any trouble remembering what this is called! I could try to make some analogy to the rock but I think I best leave it be.
Good word, Joy! - that is the exactly correct word for this occurrence. The deposits in the veins can come from hot gases or simply from groundwater over time. The larger the crystals, the longer they have taken to form. You will almost always find calcite and/or quartz (silica) in these sort of infillings. and this looks more like granite (acidic minerals: feldspar, quartz and amphiboles) than basalt (usually the more basic minerals and darker.)
Reminds me alot of the Canadian Sheild where I grew up, Joy. Ah the memories! :)
I was wondering what language I should choose for this title. Then I read. Looks like you've done a great job of research. Norrel has used his new word in three sentences. I wonder if it stuck with him. I hope that amygdules sticks in Norrel's head. He may need to use the word amygdules again sometime. I doubt that I will ever need to say amygdules again but I do need to find the word amygdules, I'll know where to find it... it'll be in my faves.
Johny Just the person I needed to come along...someone who really knows what this is all about. I just have one question left. I meant to say that I thought the large rock with the pipe amygdules was basalt. It is the dark reddish purplish smooth solid looking rock. But now I look up basalt & it is black. But this rock does not look like the things I associated with the different colors of granite that I know of. Argh! I am too tired to think as I have been helping a friend move furniture all day. I looked and looked because I thought amygdules was the word I remembered but all the photos showed round or almond shaped ones then on a Lake Superior geology site I found the term pipe amygdules in relation to the geology of the area where the photo is from - so that seemed to make sense. Hope you can make heads or tails of this. I forgot to say that the rock is under the waves - had to wait for just the right second to take the shot.
Jean Thanks for taking this photo to your collection! It is probably the only one where the title is more catchy than the photo!
n1w....Amy G Dules, you know her don't you?
I do now!
:) Have a look at what else I discovered in the photo when I was trying to look at the rock closer to see if I could make it look like granite. I just uploaded it.
The orange colour in some granites is caused by orthoclase feldspar which is orange in colur. Granites can come in lots of colours as you say from white to black depending on the type of feldspar that is in it and depending on the percentage of each of the three main constituents that I listed above.
I love this picture, JF, it would make a great abstract! I also enjoyed the lesson on Amygdules, and will do my best to remember it all as I hear there may be a surprise test ;D Theolfa
Johny if I understand correctly the big rock is granite with feldspar in it that gives it the reddish color. So the correct title should be Granite with Pipe Amygdules? I have to take a closer look at this rock when I am up that way next.
Theolfa I posted a close up as an abstract today. I was enlarging it to look at the rock and discovered little shiny spots that almost looked like cells in a blood stream. I think perhaps they are water bubbles??? If you are right about the test I think I still may fail. LOL!
Yes Joy that would work.
(Just a side note, sometimes these cracks or 'vugs' form after the fact during cooling and are simply filled later with other minerals meaning they would not actually be amygdules.)
I struggled with this as I read about it to begin with but this all started when I read about the geology at the nature center there. To the best of my memory they used the term amygdules. Then when I was walking on the beach I was excited to spot these and that started all the research. So hopefully that is the correct term in this case. Thanks for all your help!
Dear Joy, I work with stones, I was prospector of new minings and now a buyer of blocks. In vulgar language we use to talk that is cracks( and this cracks comes after the granit formation and the cause is because have intrusions of the another type of mineral. Greetings. Silvy.
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Photo taken in Cook County, MN, USA
Misplaced? Suggest new location