Crystal Forms (original) (raw)

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JCrystal

Paper Models

Steffen Weber has created a replacement version of JCrystal called KrystalShaper that can produce paper models of the example crystals on the crystallography section of Webmineral. Paper models for the 32 crystal classes and 7 crystal systems have been reproduced in .pdf format. These models can be printed on heavy card stock to construct a physical model. Please note: the paper model forms may be simplified from the JCrystal forms to avoid overly-complicated cut-outs.

Students may want to try and construct a physical model of the crystal forms for illustration purposes. These models will help teach symmetry operations needed to identify crystal forms. The student is encouraged to mark on the paper models noting mirror planes and rotational axes.

Link to paper model PDF files: Isometric Tetragonal Orthorhombic Hexagonal Trigonal Monoclinic Triclinic

Instructions:

1. Select the paper crystal model by clicking on the thumbnail image. You may want to try the crystal system models first because of the simpler shape.
2. Print in landscape mode on Heavy Paper Card Stock (60-70 lb/ream) for best results. You want paper about the thickness of a postcard. Use 8.5x11 or A4 size. For a larger model, you can use 11x17 or tabloid sizes if your printer can handle the larger paper sizes.
3. Cut along lines using a sharp scissors or a blade cutter (Exacto� knife) on a cutting mat.
4. Crease and fold the tabs and crystal faces along the pre-printed lines. Use an awl or mechanical pencil tip (with the lead retracted) to crease the paper along the lines.
5. Test fold crystal form to check fit.
6. Apply White Glue on Tabs, one pair at a time using Toothpick.
7. Hold Tabs Together until Dry.
8. Repeat for all Tabs.

Crystal System	Class Name	AXES	Planes	Center	Paper Model forms (PDF Image)
2 Fold	3 Fold	4 Fold	6 Fold
Isometric	Tetartoidal	3	4	-	-	-	-	23
Diploidal	3	4	-	-	3	yes	2/m 3
Hextetrahedral	3	4	-	-	6	-	4 3m
Gyroidal	6	4	3	-	-	-	432
Hexoctahedral	6	4	3	-	9	yes	4/m 3 2/m
Tetragonal	Disphenoidal	1	-	-	-	-	-	4
Pyramidal	-	-	1	-	-	-	4
Dipyramidal	-	-	1	-	1	yes	4/m
Scalenohedral	3	-	-	-	2	-	4 2m
Ditetragonal pyramidal	-	-	-	-	4	-	4mm
Trapezohedral	4	-	1	-	-	-	422
Ditetragonal- Dipyramidal	4	-	1	-	5	yes	4/m 2/m 2/m
Orthorhombic	Pyramidal	1	-	-	-	2	-	mm2
Disphenoidal	3	-	-	-	-	-	222
Dipyramidal	3	-	-	-	3	yes	2/m 2/m 2/m
Hexagonal	Trigonal Dipyramidal	-	1	-	-	1	-	6
Pyramidal	-	-	-	1	-	-	6
Dipyramidal	-	-	-	1	1	yes	6/m
Ditrigonal Dipyramidal	3	1	-	-	4	-	6m2
Dihexagonal Pyramidal	-	-	-	1	6	-	6mm
Trapezohedral	6	-	-	1	-	-	622
Dihexagonal Dipyramidal	6	-	-	1	7	yes	6/m 2/m 2/m
Trigonal	Pyramidal	-	1	-	-	-	-	3
Rhombohedral	-	1	-	-	-	yes	3
Ditrigonal Pyramidal	-	1	-	-	3	-	3m
Trapezohedral	3	1	-	-	-	-	32
Hexagonal Scalenohedral	3	1	-	-	3	yes	3 2/m
Monoclinic	Domatic	-	-	-	-	1	-	m
Sphenoidal	1	-	-	-	-	-	2
Prismatic	1	-	-	-	1	yes	2/m
Triclinic	Pedial	-	-	-	-	-	-	1
Pinacoidal	-	-	-	-	-	yes	1

Other References to Crystal Forms

Here is an e-mail I received from Uwe Kolitsch on referencing brackets in mineral nomenclature.

Hi Uwe,

I was always a little fuzzy on the protocols for using ....[ { ( <..... in mineralogical references. Thanks for the pointers. They didn't teach this stuff in the dark ages when I took my mineralogy course. Or if they did teach it, there were too many years between then and now when I needed to use it.

This is important stuff and I need to pay more attention. Since webmineral is created from a database, all I have to do is modify the programs that create the "data" and "Java" pages. I also need to review the supporting pages in the crystallography section and be sure the brackets are correctly used. I will probably modify the help pages to clarify the information you kindly provided.

Thanks,
Dave

Hi Dave,
I noted that crystal forms and faces/planes on webmineral are incorrectly written (I hope my following advice is helpful):
Example1:
Schultenite - Cleavage: [010] Good
(should read: ... (010) Good or {100} Good)
Example 2:
Schultenite - Forms: [ 0 1 1] [ 1 2 1] [ 0 1 0] [ 1 4 0] [ 1 1 1] [ 1 3 0] [ 0 0 1]
(should read: Forms: {011} etc.)
There are some general rules:

• (Single) crystal faces/planes are written (...)
  e.g. (110), (1-10) etc.
• Crystal forms are written {...}
  e.g. {100} in the cubic system comprises the set of the following 6 symmetry-equivalent faces/planes: (100), (-100), (010), (0-10), (001) and (00-1).
• Directions in a crystal (zone axes) are written [...] [ uvw ]
  e.g., [100] = direction along the a-axis
• A set of all symmetry-equivalent direction is written <...> (e.g., <100> for halite = directions [100], [-100], [010], [0-10] etc.)
• [Note: d-spacings hkl are written without any parentheses (e.g., "the 311 reflection").]

see
http://www.gly.uga.edu/schroeder/geol3010/3010lecture06.html
http://www.rockhounds.com/rockshop/xtal/part7.html
http://www.stanford.edu/group/glam/xlab/MatSci162_172/LectureNotes/02_Geometry,%20RecLattice.pdf
Cheers, Uwe
*********************************************
Priv.-Doz. Dr. Uwe Kolitsch
Institut f�r Mineralogie und Kristallographie
Geozentrum, Universit�t Wien
Althanstr. 14
A-1090 Wien
Austria

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