1. Color is useful in recognizing some minerals, but not all N. Lindsley-Griffin, 1998

2. Color adds value to gems N. Lindsley-Griffin, 1999

3. Streak, the color of the mineral’s powder, may be more useful than color in identifying a mineral N. Lindsley-Griffin, 1998

4. © Houghton Mifflin 1998; Lindsley, 2000 The silicon-oxygen tetrahedron is the building block of silicate minerals Four oxygen ions surround a much smaller silicon ion Structure of Silicate Minerals Most rocks consist of silicate minerals.

5. The silicate tetrahedron consists of 4 large oxygen atoms around a smaller silicon atom Two tetrahedrons link together by sharing an oxygen at one corner Expanded View N. Lindsley-Griffin, 1999

6. Silicate tetrahedrons can form chains, sheets, and three-dimensional nets by sharing their oxygen atoms. Each influences mineral properties. N. Lindsley-Grifin, 1999

7. Tetrahedral Linkages © Houghton Mifflin 1998. All rights reserved A. Isolated tetrahedra - Olivine B. Single chain - Pyroxene C. Double chain - Amphibole D. Sheets - Micas, clay, talc E. Framework - Quartz, feldspar

8. Polymorphs are minerals with the same chemical composition, but different internal atomic structures N. Lindsley-Griffin, 1998

9. © Houghton Mifflin 1998; N. Lindsley-Griffin, 1999. All rights reserved SUMMARY: PHYSICAL PROPERTIES of MINERALS Crystal Structure Crystal Form Interfacial Angles Habit Cleavage Fracture Hardness Luster Color Streak Specific Gravity (Density)