Properties of Minerals Scientists use characteristics to tell one mineral from another

Mineral Properties we will be investigating: Luster Hardness Streak Transparency

Luster 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.

Pyrite has metallic luster

Quartz has nonmetallic luster

Hardness Is measured by how easy it is to scratch. Geologists order the hardness by… –Scratched by a fingernail. –Scratched by a penny. –Scratched by a nail. –Scratched by a diamond. These are not all of the tools geologists use, but it will work for now when we perform an experiment.

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.

Transparency Transparency describes how much light is able to pass through a mineral

Streak Red chalk on a chalk board makes red marks. White chalk makes white marks. When some minerals are scratched along a ceramic streak plate they create different colors.

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

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.

Shape

One mineral property we will not use… COLOR

A mineral can be many different colors. Below are samples of Mica.

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

The answer… None of them were real gold.