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Thread: Rocks, That Is All

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    Beloved Curmudgeon DaVegaNL's Avatar
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    Rocks, That Is All

    Rocks.

    That's all.

  2. #2
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    Quote Originally Posted by DaVegaNL View Post
    Rocks.

    That's all.
    Since you pointed out awhile back that you are a geologist, I wanted to know why some rocks seem to form in uniform patterns.
    This link below shows some Magnetite but it looks as if someone through together a bunch of triangles.

    Why would something be found like that?



    https://en.wikipedia.org/wiki/Magnetite

    You can click on the photo to get a closer look.

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    Quote Originally Posted by sillls View Post
    Since you pointed out awhile back that you are a geologist, I wanted to know why some rocks seem to form in uniform patterns.
    This link below shows some Magnetite but it looks as if someone through together a bunch of triangles.

    Why would something be found like that?



    https://en.wikipedia.org/wiki/Magnetite

    You can click on the photo to get a closer look.
    Crystals.

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    Colon Pounder The Gronk's Avatar
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    Quote Originally Posted by sillls View Post
    <snipped for space>
    The short answer is crystallization. It happens when the atoms have the opportunity to arrange themselves into repeating structures. The variables are pressure, heat, time and weathering (plus others).

    https://en.wikipedia.org/wiki/Crystallization

    There are some oddities such as the chernobylite crystals which are only found in the corium at Chernobyl.

    There are also crystals that have a structure that repeats over time, never truly becoming a single solid crystal. These are called time-crystals are are about the single most Dr Who sounding substance we have found :-)

    https://en.wikipedia.org/wiki/Time_Crystal

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    Crystals yes, sorry about that. But look how at the straight lines. How can that happen naturally?

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    Colon Pounder The Gronk's Avatar
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    Quote Originally Posted by sillls View Post
    Crystals yes, sorry about that. But look how at the straight lines. How can that happen naturally?
    Oh, right :-)

    That largely depends on how the molecules fit together. Different shaped molecules will tessellate together in different patterns. Cubic and hexagonal are very common ones.

    This vid explains it far better than I could...

    https://www.youtube.com/watch?v=NgD9yHSJ29I

    This vid shows salt crystals forming but the process is pretty much the same for any crystal.

    https://www.youtube.com/watch?v=ZTG8FCJZL3M
    Last edited by The Gronk; 08-12-2019 at 12:19 AM.

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    Quote Originally Posted by sillls View Post
    Crystals yes, sorry about that. But look how at the straight lines. How can that happen naturally?
    As Gronk said, Chemistry bits That first vid is really well done (haven't watched the second yet).

    Reminded me of how I used to remember the difference between ionic & covalent bonds.
    -- I'd think "Iconic" instead of "ionic", as Iconic sort of means 'one' or 'singular'
    -- for covalent, well, it was easy to think of this as 'codependent' or 'couple'. more than one. (had a wild n crazy gf that semester)

    If you want more you might try searching for "chemistry molecular bonds" & "chemistry cubic structures".
    For some really cool (to me) stuff you might look at https://en.wikipedia.org/wiki/Tempering_(metallurgy) since tempering is basically the intentional manipulation of how much and what type of crystalline structures a piece of steel will have.

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    Quote Originally Posted by The Gronk View Post
    Oh, right :-)

    That largely depends on how the molecules fit together. Different shaped molecules will tessellate together in different patterns. Cubic and hexagonal are very common ones.

    This vid explains it far better than I could...

    https://www.youtube.com/watch?v=NgD9yHSJ29I

    This vid shows salt crystals forming but the process is pretty much the same for any crystal.

    https://www.youtube.com/watch?v=ZTG8FCJZL3M
    Thanks for the two links. The second one was even better. But one thing that I don't understand is how do you get squares and triangles
    out of round drops of salty water. Some did seem to start forming round but still formed straights edges.

    Seems that they should have formed round like the drop but they didn't.

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    Colon Pounder The Gronk's Avatar
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    Quote Originally Posted by sillls View Post
    Thanks for the two links. The second one was even better. But one thing that I don't understand is how do you get squares and triangles
    out of round drops of salty water. Some did seem to start forming round but still formed straights edges.

    Seems that they should have formed round like the drop but they didn't.
    Well spotted that the centres are often far more chaotic than the full grown crystal. :-)

    I'll try to explain this in simpler terms.

    The molecules have an easier time bonding with other molecules if the pattern has no flaws. Over the course of time the areas where the pattern has no flaws grow faster than those areas that do have flaws. What you're seeing is that part of the pattern which has grown the fastest, often swamping and smothering the other crystal edges that are forming and stopping them in their tracks. This causes a chaotic centre surrounded by a very uniform shell.

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    Quote Originally Posted by The Gronk View Post
    Well spotted that the centres are often far more chaotic than the full grown crystal. :-)

    I'll try to explain this in simpler terms.

    The molecules have an easier time bonding with other molecules if the pattern has no flaws. Over the course of time the areas where the pattern has no flaws grow faster than those areas that do have flaws. What you're seeing is that part of the pattern which has grown the fastest, often swamping and smothering the other crystal edges that are forming and stopping them in their tracks. This causes a chaotic centre surrounded by a very uniform shell.
    So it's kind of like a key and a lock. The atoms fit best in a uniform pattern. Pulling other atoms to it as it grows and attach themselves best at those points.

    I see now.
    Thanks.

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    Fun Pimps Staff Gazz's Avatar
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    Quote Originally Posted by sillls View Post
    Crystals yes, sorry about that. But look how at the straight lines. How can that happen naturally?
    Because crystals are natural. =P
    If a magma pocket very slowly cools down then crystals can form. Minerals have very specific axis along which they want to bond, given the chance. The random part is the occurrence of the conditions, not the shape of the crystal.

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    Beloved Curmudgeon DaVegaNL's Avatar
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    Quote Originally Posted by sillls View Post
    Since you pointed out awhile back that you are a geologist, I wanted to know why some rocks seem to form in uniform patterns.
    This link below shows some Magnetite but it looks as if someone through together a bunch of triangles.

    Why would something be found like that?

    https://en.wikipedia.org/wiki/Magnetite

    You can click on the photo to get a closer look.
    Yeah it's due to the crystalline shapes certain mineral compounds form in nature. I'm not a chemist, so I can't explain exactly why these crystal forms take the form they have, but think for example of carbon. In graphite for example, the carbon atoms are arranged quite differently then in diamond, even though they are completely made up of pure carbon, resulting in very different material properties.

    Some minerals (like galena, the lead ore modelled here in-game) have a rather cubic shape, whilst others are more hexagonic or monoclinal etc.

    Hope this helps!

    - - - Updated - - -

    Quote Originally Posted by The Gronk View Post
    The short answer is crystallization. It happens when the atoms have the opportunity to arrange themselves into repeating structures. The variables are pressure, heat, time and weathering (plus others).

    https://en.wikipedia.org/wiki/Crystallization

    There are some oddities such as the chernobylite crystals which are only found in the corium at Chernobyl.

    There are also crystals that have a structure that repeats over time, never truly becoming a single solid crystal. These are called time-crystals are are about the single most Dr Who sounding substance we have found :-)

    https://en.wikipedia.org/wiki/Time_Crystal
    Dude, you are stealing my thunder! Even though weathering does not have an influence on the pure shape of the crystals.

  13. #13
    Beloved Curmudgeon DaVegaNL's Avatar
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    Quote Originally Posted by Gazz View Post
    Because crystals are natural. =P
    If a magma pocket very slowly cools down then crystals can form. Minerals have very specific axis along which they want to bond, given the chance. The random part is the occurrence of the conditions, not the shape of the crystal.
    *Throws down my pet-rock*

    Looks like everybody is a geologist here now! ^-^

    Yeah you are right. If magma cools sufficiently slow you can get very nice and large crystals, also called plutonic rocks (granite, for example). If the magma extrudes to the surface, it cools down much more rapidly. Because of this, there is not enough time to form large crystals, because of which you can get a more 'homogenous' rock (basalt, for example).

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    should we expect the experimental and 18 in the 20 days

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    Reconstructionist A Nice Cup of Tea's Avatar
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    Quote Originally Posted by DaVegaNL View Post
    *Throws down my pet-rock*

    Looks like everybody is a geologist here now! ^-^

    Yeah you are right. If magma cools sufficiently slow you can get very nice and large crystals, also called plutonic rocks (granite, for example). If the magma extrudes to the surface, it cools down much more rapidly. Because of this, there is not enough time to form large crystals, because of which you can get a more 'homogenous' rock (basalt, for example).
    We should be able to make obsidian knives and spear tips.

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