Rock Cycle - Minerals (3A) Post Lab
 OBJECTIVES: Distinguishing the geometric shapes of minerals. Comparing Platonic and Archimedean solids. VOCABULARY: cube dipyramid dodecahedron hextetrahedron parallelogram prism MATERIALS: Googolplex, zometool, polyconstructo or any geometric building set Students compare the shapes of minerals with geometric figures.
 BACKGROUND: Geometric shapes help describe minerals. A platonic solid is composed of a single repeated polygon. The five platonic solids are the tetrahedron (4 triangles), cube (6 squares), icosahedron (20 triangles), octahedron (8 triangles) and dodecahedron (12 pentagons). The Archimedean solids are composed of combinations of polygons and named after the Greek philosopher Archimedes. The Greek philosopher Plato, who was born around 430 B.C., wrote about these five solids in a work called Timaeus. Historical accounts vary a little, but it is usually agreed that the solids themselves were discovered by the early Pythagoreans, perhaps by 450 B.C. There is evidence that the Egyptians knew about at least three of the solids; their work influenced the Pythagoreans. In any case, Plato mentioned these solids in his writings He identified them with the elements then commonly believed to make up all matter in the universe; fire, air, water, earth, and the cosmos (the universe itself). Plato identified fire atoms with the tetrahedron, earth atoms with the cube, air atoms with the octahedron, water atoms with the icosahedron, and the cosmos atoms with the dodecahedron. PROCEDURE: Have the students make their own geometric forms using Googolplex. Use the workbooks to direct their work. You may wish to have the students work in groups.    You may want the students to determine the geometries of the mineral specimens that they used in the lab. The following key lists the geometric shapes of the lab specimens, along those of some other common minerals .    QUARTZ, AMETHYST, CITRINE (prism with six sides) CALCITE, FELDSPAR, GYPSUM (3d parallelogram or rhombohedron) HALITE, PYRITE, GALENA, (cube) GARNET (dodecahedron (12 sides)) DIAMOND (hexatetrahedron or dipyramid (8 sides)) FLUORITE (isohedron)
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