Rock Cycle - Minerals (3B)
Pre Lab 

   
OBJECTIVES:
  • Distinguishing between crystalline and amorphous substances.
  • Recognizing crystalline substances.
VOCABULARY:
  • amorphous
  • crystalline 
MATERIALS:
  • worksheet

Students create patterns using Altair designs.


Electron level picture of tin

BACKGROUND:

The atoms in crystalline solid matter are arranged in regular, repeating .patterns. All other types of solid matter are amorphous or without a regular atomic arrangement. Metals and minerals are crystalline. Glass is amorphous. Depending upon its composition, the crystalline pattern of a mineral may not be visible in a hand sample. In this case minerals are studied using X-ray diffraction, a technique that uses the reflection of X-rays to determine crystal structure and composition.

PROCEDURE:

  1. Draw the following diagram on the board to illustrate crystalline versus a non-crystalline (amorphous) patterns.


crystalline


amorphous

  1. On the worksheet, have the students outline or fill in spaces on the Altair designs sheet to create patterns. Their patterns are examples of order within the overall structure of the design. This same type of organization generates crystalline structures in minerals. The Altair designs sheet will naturally guide each studentís imagination through the maze of lines. Since no two students are alike, none of them will see the same shapes, forms or patterns hidden in these designs. They may create some very interesting artwork.
      

  2. After the students finish their patterns, see if there are any similar patterns. Use any similarities and differences to reinforce that there are many types of minerals, and hence many different crystal patterns.

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