Mineral Properties

Activity #15Mineral PropertiesKey ConceptsA pure substance, such as a mineral, can be identified from observations and tests performed to determine its physical properties. These properties are based on the unique structure of the substance.Minerals are crystals that form naturally in the Earth. They have characteristic properties, such as color, hardness, and a crystalline shape. Rocks are made of minerals. Vocabulary Crystalline structure the regular pattern of atoms, molecules or ions in a crystal.

Geologist scientist who studies the Earth and the changes that take place on and beneath the surface

VocabularyMineral a naturally occurring solid material that has a specific chemical composition and crystal form and characteristic physical properties. There are about 3,500 different minerals.Rock a naturally occurring solid substance composed of one or more minerals.Minerals/4 Characteristics Forms in nature Is a solidHas a definite chemical make-upHas a crystal structureMinerals Form In NatureFormed by natural processes. Are inorganic which means they are made of non-living materials found naturally on earth. Minerals are SolidsA mineral has a definite volume and a rigid shape.Volume refers to the amount of space an object takes up

Definite Chemical Make-upEvery mineral consists of a specific combination of atoms of certain elements.The types of atoms that make up a mineral are part of what makes the mineral unique.The way in which the atoms are bonded, or joined together, is also important.Many properties of minerals are related to how strong or weak the bonds are. Crystal Structure The way the atoms are arranged in an orderly, repeating three-dimensional pattern.Each mineral has its own type of crystal structure.Minerals can have the same chemical compound/same type of atoms, but the way the atoms are arranged is different.Diamonds and graphite are made of the same element, carbon, but the arrangement of these carbon atoms is different. Mineral PropertiesMinerals have characteristic properties that are used to identify them:1. color5. Fracture2. luster6. Density3. transparency 7. crystalline structure4. streak color8. crystal habit (shape)

Look at the following minerals. Which do you think are the same types of minerals and which do you think are different?

the same type of mineral! They are examples of quartz!!Haha! Tricked you! These are all

There are over 3000 types of minerals in the Earths crust

As you could see with the quartz, often times even the same kind of minerals can look very different

Therefore, geologists (scientists who study minerals and rocks) often use several different tests to determine type of a mineral they have found!

Why Is It So Difficult toIdentify Minerals?

Color is obviously one of the most noticeable characteristics of a mineral, but it also the least reliable of all the characteristics

The color of a mineral is often caused by tiny amounts of other elements or compounds insideFor example, what people call amethyst is actually just quartz with iron in it!Color

The way that a mineral reflects light from its surface is its lusterThe two types of luster are:- metallic- nonmetallicLuster

Metallic LusterTexture describes how a mineral feels to the touch.

Minerals can range anywhere between glassy feeling, rough feeling, greasy feeling, and even soapy feeling!Texture

Talc has a soapy texture.

Fluorite has a glassy texture.When a mineral is rubbed against a tile, it will leave behind a colored powdered streak on the tileSometimes a minerals streak does not match the minerals external colorFor example, one way to tell the difference between pyrite (Fools gold) and real gold is by streak. Pyrite leaves a greenish-black streak while real gold leaves a yellow streak.Streak

Hardness is a measure of how easily a mineral can be scratchedGeologists use Mohs scale to give minerals their hardness ratingsHardness

HardnessMineralAssociations and Uses1TalcTalcum powder.2GypsumPlaster of paris. Gypsum is formed when seawater evaporates from the Earths surface.3CalciteLimestone and most shells contain calcite.4FluoriteFluorine in fluorite prevents tooth decay.5ApatiteWhen you are hungry you have a big "appetite".6OrthoclaseOrthoclase is a feldspar, and in German, "feld" means "field".7Quartz8TopazThe November birthstone. Emerald and aquamarine are varieties of beryl with a hardness of 8.9CorundumSapphire and ruby are varieties of corundum. Twice as hard as topaz.10DiamondUsed in jewelry and cutting tools. Four times as hard as corundum.The pattern of atoms will determine how a mineral will breakA mineral that breaks relatively easily and evenly at angles is said to have cleavage

Minerals that break with rough or jagged edges are said to have fractureCleavage and Fracture

Some minerals have unique propertiesFor example, Iceland spar can create double images

Some minerals react with hydrochloric acid and release carbon dioxide (bubbles)Some Other Special Properties