Color is useful in recognizing some minerals, but not all

N. Lindsley-Griffin, 1998

Color adds value to gems

N. Lindsley-Griffin, 1999

Streak, the color of the mineral’s powder, may be more useful than color in

identifying a mineral

N. Lindsley-Griffin, 1998

© 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

Structure of Silicate Minerals

Most rocks consist of silicate minerals.

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

Silicate tetrahedrons can form chains, sheets, and three-dimensional nets by

sharing their oxygen atoms. Each influences mineral properties.

N. Lindsley-Grifin, 1999

Tetrahedral Linkages

© Houghton Mifflin 1998. All rights reserved

A. Isolated tetrahedra - OlivineB. Single chain - PyroxeneC. Double chain - AmphiboleD. Sheets - Micas, clay, talcE. Framework - Quartz, feldspar

Polymorphs are minerals with the same chemical composition, but

different internal atomic structures

N. Lindsley-Griffin, 1998

© Houghton Mifflin 1998; N. Lindsley-Griffin, 1999. All rights reserved

SUMMARY: PHYSICAL PROPERTIES of MINERALS

Crystal StructureCrystal Form Interfacial AnglesHabitCleavageFracture

Hardness LusterColor StreakSpecific Gravity (Density)