GY 302: Crystallography and Mineralogy (2010) Lab Assignment 2: Tetragonal & Orthorhombic Crystallography Your Task: Well, here we go again. This lab exercise continues your introduction to elements of symmetry in crystals and how to identify them. In this lab, we will focus on the tetragonal and orthorhombic crystal systems. Select 2 wooden crystal models from each of the 2 groups listed below and answer the following questions: 1) How many mirror planes does it have? 2) How many 2 fold, 3 fold, 4 fold or 6 fold rotational axes does it have? 3) What is it's highest rotational symmetry? 4) Does it have any rotoinversion axes? (3-fold and higher) 5) Does it have a center of inversion? 6) What is its point group? 7) Draw a stick diagram for each of the models and, 8) Draw an approximate stereonet projection for each of the models In total, I expect 4 answer sheets from you (2 orthorhombic minerals; 2 tetragonal minerals by the due date). Make sure that you indicate the number of the model you do in the space provided on the answer sheets. Due Date: See calendar or website for dues date. Orthorhombic Crystals: Large models: 42, 132, 133, 135, 136, 138, 140, 141, 143, 149, 153, 154, 156, 157, 183 Small models: 24, 26, 27, 143, 152, 154, 156, 165, 166, 183, 202 Tetragonal Crystals: Large models: 53, 54, 57, 58, 59, 60, 61, 62, 66, 68, 69, 71A, 72, 73, 77, 79, 80 Small models: 21b, 61, 66, 67, 73, 76, 78, 83, 87, 89, 93, 169Orthorhombic and Tetragonal Models Name: _____________________________________ Date: ________________ Model Number: ___________ Crystal Class ________________ 1) How many mirror planes does it have? ____________________________________________ 2) How many 2 fold rotational axes does it have? ______________________________________ 3) How many 3 fold rotational axes does it have? ______________________________________ 4) How many 4 fold rotational axes does it have? ______________________________________ 5) How many 6 fold rotational axes does it have? ______________________________________ 6) What is the highest rotational symmetry of the model?________________________________ 7) Are any of the axes (above 2-fold) rotoinversion axes (e.g. 3 and above)? Yes No (indicate which on questions 2-6) 8) Does the model have a center of inversion? Yes No 9) What is the point group of the model? __________________________________________ Stick DiagramOrthorhombic and Tetragonal Models Name: _____________________________________ Date: ________________ Model Number: ___________ Crystal Class ________________ 1) How many mirror planes does it have? ____________________________________________ 2) How many 2 fold rotational axes does it have? ______________________________________ 3) How many 3 fold rotational axes does it have? ______________________________________ 4) How many 4 fold rotational axes does it have? ______________________________________ 5) How many 6 fold rotational axes does it have? ______________________________________ 6) What is the highest rotational symmetry of the model?________________________________ 7) Are any of the axes (above 2-fold) rotoinversion axes (e.g. 3 and above)? Yes No (indicate which on questions 2-6) 8) Does the model have a center of inversion? Yes No 9) What is the point group of the model? __________________________________________ Stick DiagramOrthorhombic and Tetragonal Models Name: _____________________________________ Date: ________________ Model Number: ___________ Crystal Class ________________ 1) How many mirror planes does it have? ____________________________________________ 2) How many 2 fold rotational axes does it have? ______________________________________ 3) How many 3 fold rotational axes does it have? ______________________________________ 4) How many 4 fold rotational axes does it have? ______________________________________ 5) How many 6 fold rotational axes does it have? ______________________________________ 6) What is the highest rotational symmetry of the model?________________________________ 7) Are any of the axes (above 2-fold) rotoinversion axes (e.g. 3 and above)? Yes No (indicate which on questions 2-6) 8) Does the model have a center of inversion? Yes No 9) What is the point group of the model? __________________________________________ Stick DiagramOrthorhombic and Tetragonal Models Name: _____________________________________ Date: ________________ Model Number: ___________ Crystal Class ________________ 1) How many mirror planes does it have? ____________________________________________ 2) How many 2 fold rotational axes does it have? ______________________________________ 3) How many 3 fold rotational axes does it have? ______________________________________ 4) How many 4 fold rotational axes does it have? ______________________________________ 5) How many 6 fold rotational axes does it have? ______________________________________ 6) What is the highest rotational symmetry of the model?________________________________ 7) Are any of the axes (above 2-fold) rotoinversion axes (e.g. 3 and above)? Yes No (indicate which on questions 2-6) 8) Does the model have a center of inversion? Yes No 9) What is the point group of the model? __________________________________________ Stick
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