IN: If you had to describe how one mineral is different from another, how might you describe its properties?

3-2 IDENTIFYING MINERALS  How are these two minerals are the same? How are they different?

PROPERTIES OF MINERALS  Color  Luster  Streak  Cleavage and Fracture  Hardness  Density  Special Properties

COLOR  The same mineral can come in different colors.  Impurities  Quartz-white, red, pink, and purple  Weathering  Pyrite turns black  Color is not a very reliable indicator of a mineral’s identity.

LUSTER  The way a surface reflects light. (How it Shines)  There are 3 types: 1. Metallic 2. Submetallic 3. Nonmetallic (vitreous, silky, resinous, waxy, Pearly or Earthy)

METALLIC LUSTER  Looks shiny, like metal.

NONMETALLIC LUSTER  Does not look like metal. Vitreous quartz Pearly talc Earthy psilomelane

 Has properties of both metallic and nonmetallic. Hematite

STREAK  The color of a mineral in a powdered form. (shows its “true color”)  The color of a mineral is not always the color of its streak.

STREAK  A minerals streak is not affected by weathering.  Therefore, a mineral’s streak is much more reliable than its color.

CLEAVAGE  The tendency of some minerals to break along flat surfaces.

FRACTURE  The tendency of some minerals to break unevenly along curved or irregular surfaces.

HARDNESS  A mineral’s resistance to being scratched.

DENSITY  The measure of how much matter there is in a given amount of space.  Remember the density of water=1g/mL

SPECIAL PROPERTIES  Properties that are particular to only a few types of minerals.

SPECIAL PROPERTIES  Fluorescence

CHEMICAL REACTION  Calcite will “fizz” with acid

OPTICAL PROPERTIES

RADIOACTIVITY  Uranium

MAGNETISM  Magnetite

TASTE  Halite  Tastes “salty”

 OUT: How would you summarize the seven properties of a mineral?