Properties of Properties of MineralsMineralsGeologists use Geologists use

characteristics to tell characteristics to tell one mineral from one mineral from

anotheranother

Mineral Properties we will Mineral Properties we will studystudy

Luster Hardness

Cleavage Streak

LusterLuster•Refers to the way light reflects

from the surface of the mineral. •There are two types of luster,

–Metallic: looks like polished metal. –Nonmetallic: does not look like polished metal. •Nonmetallic can be shiny or dull.

Pyrite has metallic Pyrite has metallic lusterluster

Quartz has nonmetallic Quartz has nonmetallic lusterluster

HardnessHardness• Is measured by how easy it is to

scratch. • Geologists order the hardness by…1. Scratched by a fingernail.2. Scratched by a penny. 3. Scratched by a nail. 4. Scratched by a diamond.

These are not all of the tools geologists use, but it will work for our experiment.

Gypsum is soft, it can be Gypsum is soft, it can be scratched by a fingernail.scratched by a fingernail.

Calcite is soft, but a little Calcite is soft, but a little harder because it cannot be harder because it cannot be

scratched by a fingernail, but it scratched by a fingernail, but it can be scratched by a penny. can be scratched by a penny.

Fluorite is harder. It can be Fluorite is harder. It can be scratched by a nail, but not a scratched by a nail, but not a

penny or fingernail. penny or fingernail.

Diamonds are the hardest Diamonds are the hardest mineral, so it scratches every mineral, so it scratches every

mineral. mineral.

CleavageCleavage•Not all minerals have cleavage. •Some minerals split easily

along a flat surface. •The number of lines that are

created when a mineral is split will be the number of cleavage lines.

Mica has cleavage in one Mica has cleavage in one direction. direction.

It breaks along one line. It breaks along one line.

Feldspar has two lines of Feldspar has two lines of cleavage. It breaks along cleavage. It breaks along

two lines. two lines.

StreakStreak• Red chalk on a chalk board

makes red marks. White chalk makes white marks.

• Not all minerals work this way. When some minerals are scratched along a ceramic streak plate, it creates a different color.

GoldGold• When gold is

run across a streak plate it makes a yellowish-gold color.

• That makes sense.

Pyrite or “Fool’s Gold”Pyrite or “Fool’s Gold”• When pyrite is run

across a streak plate, it has a black or dark green streak.

• Pyrite is not worth much money, while gold is worth a lot. They look alike, so miners call it fool’s gold.

HematiteHematite• Hematite’s color is

grey, but its streak is red.

• Hema means blood. • The mineral was

named hematite because it looked like it was bleeding when it was taken across a streak plate.

One mineral One mineral property we will property we will

notnot use… use…COLORCOLOR

A mineral can be many A mineral can be many different colors. Below is Mica.different colors. Below is Mica.

Many minerals can be the same color. Many minerals can be the same color. Below are gold colored minerals. Which one Below are gold colored minerals. Which one

is gold?is gold?

The answer…The answer…None of them None of them

were real gold. were real gold.

Just like with people…Just like with people…

Outside color does not tell Outside color does not tell you much about the you much about the

important characteristics. important characteristics.