Lesson #12 Properties of Minerals Objective: learn how to use characteristics to tell one mineral from another Bellringer: Grab the handout from the front and have a seat. Fill out ToC, lesson, and objective in your notebook

Mineral Characteristics Earth’s crust is composed of about 3000 different minerals

Mineral Characteristics A mineral: Is naturally occurring Is inorganic solid Has a specific chemical composition Has definite crystalline structure

Mineral Characteristics Naturally occurring and inorganic naturally occurring - formed by natural process inorganic - they are not from living things Is coal a mineral?

Mineral Characteristics Specific chemical composition

Mineral Characteristics Definite crystalline structure atoms are arranged in regular, repeated, geometric patterns that result in the formation of a crystal.

Mineral Characteristics Definite crystalline structure Feldspar Diamond Quartz Apetite

Identifying Minerals identify minerals using tests based on a mineral’s physical and chemical properties: crystal form luster hardness cleavage fracture streak color specific gravity texture density

Luster Refers to the way light reflects from the surface of the mineral. two types; Metallic: looks like polished metal. Nonmetallic: shiny or dull.

Pyrite has metallic luster

Quartz has nonmetallic luster

Hardness Is measured by how easy it is to scratch. order; Scratched by a fingernail. Scratched by a penny. Scratched by an iron nail. Scratched by a diamond. .

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

Calcite is soft, but a little harder because it cannot be scratched by a fingernail, but it can be scratched by a penny.

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

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

Cleavage Not all minerals have cleavage. Some minerals split easily along a flat surface. The number of lines that are created when split = cleavage lines.

Mica has cleavage in one direction. It breaks along one line.

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

Fracture When minerals break along uneven, rough, or jagged edges Think of a bone fracture

Fracture

Streak 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.

Gold When gold is run across a streak plate it makes a yellowish-gold color. That makes sense.

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.

Hematite 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 property we will not use… COLOR

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

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

None of them were real gold. The answer… None of them were real gold.