Post subject: Crystal Systems - confused with the axes
Posted: Mon Jun 25, 2012 4:54 pm
Valued Contributor
Joined: Thu May 18, 2006 5:08 am Posts: 481 Location: Kuala Lumpur
Hey guys.
I am just trying to understand crystal symmetry still (I think I need a thorough video presentation for my brain!) I understand now and can visualise all the axes of symmetry except 4 three fold axes. Now I understand that these go from corner to corner of a cube - 8 corners, 4 axes...... but how can it only be 3 fold - wouldn't a cube look the same 4 times it if was rotated around this axes?
Thank you to anyone who can explain this in blonde
_________________ Intensive jewellery making classes in the heart of South East Asia www.lucywalkerjewellery.com
Post subject: Re: Crystal Systems - confused with the axes
Posted: Mon Jun 25, 2012 5:33 pm
Moderator
Joined: Thu Dec 13, 2007 3:42 pm Posts: 4091 Location: the Netherlands
I'm a blonde...
Lucy... try a dodecahedron rather than a cube and it will be immediately clear what they mean with 4 3-fold axes.
May I suggest you download google sketchup and load this model into it. Read its description. Figure out how to work with sketchup here. (its REALLY EASY)
All other crystal systems can be downloaded via Google's 3D warehouse.
Post subject: Re: Crystal Systems - confused with the axes
Posted: Tue Jun 26, 2012 6:17 am
Moderator
Joined: Thu Dec 13, 2007 3:42 pm Posts: 4091 Location: the Netherlands
You just need to see it once...
Anybody running into the same problem could always download the paper models provided for every crystal form over at webmineral.com and create a cardboard reference set as an alternative to digital 3D modelling.
Post subject: Re: Crystal Systems - confused with the axes
Posted: Tue Jun 26, 2012 10:00 am
Valued Contributor
Joined: Thu May 18, 2006 5:08 am Posts: 481 Location: Kuala Lumpur
Thanks again Tim!
Now onto the rest!
It just seems to me, that the Gem-A course notes don't want to expand, they just want you to remember the numbers - but if I don't understand why, I can't remember them! All I want is diagrams of each system, detailing where all these damn axes and planes are as sometimes they aren't so obvious My tutor isn't so on the ball unfortunately!
I will post any decent links I find here for anyone else confused in the future
_________________ Intensive jewellery making classes in the heart of South East Asia www.lucywalkerjewellery.com
Post subject: Re: Crystal Systems - confused with the axes
Posted: Tue Jun 26, 2012 5:21 pm
Valued Contributor
Joined: Thu May 18, 2006 5:08 am Posts: 481 Location: Kuala Lumpur
Its not actually in the course notes in any detail frank. Just to be able to answer the questions in the exam I like to fully understand and not just learn the answer parrot fashion
_________________ Intensive jewellery making classes in the heart of South East Asia www.lucywalkerjewellery.com
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