Science 6th Grade Chapter 3 Properties of Minerals

How would you test a mineral to determine whether it has cleavage or fracture?

Break the mineral and see if it breaks clean and easily in one direction (cleavage) or if it breaks in a rough, irregular, uneven surface (fracture).

What is the difference between fracture and cleavage?

Cleavage is a clean split along a flat surface. It breaks apart easier in one direction than another. Fractures break apart in an irregular way.

Graphite is a mineral made up of carbon atoms that form thin sheets. But the sheets are only weakly held together. Predict whether graphite will break apart with fracture or cleavage. Explain.

Cleavage. Because the thin sheets will break apart easily in one direction but not the other.

What are the characteristic properties that can be used to identify minerals?

Color, streak, luster, density, hardness, crystal systems, cleavage and fracture, and special properties.

name eight properties that can be used to identify minerals:

Color, streak, luster, density, hardness, crystal systems, cleavage and fracture, and special properties.

Crystal Systems

Geologist classify these structures into six groups based on the number and angle of the crystal faces.

Fracture

Geologist use a variety of terms to describe this property of a mineral such as shell-shaped, hackly -form jagged points, earthy - crumble easily,

What factor affects the size of the crystals that form as magma cools?

How fast it cools. Cooling faster produces smaller crystals. Cooling slower produces larger crystals.

Cleavage

If a mineral splits easily along flat surfaces it has this property.

cleavage and fracture

break mineral apart to see if it splits along flat surfaces

What are two ways in which minerals can form from a solution?

by evaporation and from hot water solutions.

Hardness

perform scratch test

fracture

how a mineral breaks apart when it does not split evenly

luster

how a mineral reflects light from its surface

solution

is a mixture in which one substance is dissolved in another.

vein

is a narrow channel or slab of a mineral that is different from the surrounding rock.

Geode

is a rounded, hollow rock that is often lined with mineral crystals.

lava

is magma that reaches the earths surface.

magma

is molten material from inside Earth that hardens to form rock.

crystallization

is the process by which atoms are arranged to form a material with a crystal structure.

What is crystallization?

is the process by which atoms are arranged to form a material with a crystal structure. In general, minerals can form in two ways by crystallization of molten material or by crystallization of materials dissolved in water.

What size crystals for when magma cools slowly?

larger crystals

luster

observe how mineral relflects light

How can you compare the density of different minerals?

?

crustal structure

observe number and angle of crystal faces

color

observe surface of mineral

Density

= Mass of mineral Volume of water displaced by mineral

What is a mineral?

A mineral is a naturally occurring, inorganic solid that has a crystal structure and a definite chemical composition. It must have all five of these characteristics to be a mineral.

?

A sample of calcite has a mass of 324 g and a volume of 120 cm3. What is its density?

Crystal Systems

Crystals of each mineral grow atom by atom to form that mineral's crystal structure.

Density

Each mineral has a characteristic __________. ___________ is the mass in a given space, or mass per unit volume. No matter how big or small a mineral sample is, the _________ of that mineral always remains the same.

How do minerals form from hot water solutions?

Magma can heat water deep underground to high temperatures causing the elements and compounds that form a mineral to dissolve in the hot water. When the solution cools the elements and compounds leave the solution and crystallize as minerals.

Solid

Minerals are always solid, with a definite volume and shape. The particles are solidly packed so tightly, they cannot move like particles in a liquid.

How do minerals form from magma and lava?

Minerals form as hot magma cools inside Earth., or as lava hardens on the surface. When these liquids cool to a solid state, they form crystals.

Definite Chemical Composition

Minerals have definite chemical composition or range of compositions. This means that a mineral always contains certain elements in definite proportions.

Fracture

Minerals that form rough, irregular surfaces when broken have an uneven __________.

Fracture

Most minerals do not split apart evenly. Instead, they break apart in this irregular way.

Amber forms when the resin of pine trees hardens into stone. Is amber a mineral? Explain.

No. It forms from part of a living thing.

Crystal Structure

Particles of a mineral line up in a pattern that repeats over and over again. This repeating pattern of the particles forms a solid called a crystal. It has flat sides, called faces, that meet at sharp edges and corners.

What process can form veins of underground minerals?

Pure metals that crystallize from hot water solution underground often form veins. Solutions of hot water and metals often flow through cracks with the rock. The the metals crystallize into veins.

Under what conditions will cooling magma produce minerals with large crystals?

When the magma cools slowly.

Special Properties

Some minerals can be identified by unique physical properties. Such as fluorescence, magnetism, radioactivity, and reaction to acids. Some have optical or electrical properties.

Hardness

The Mohs _________ scale is a tool we can use to help with this property of a mineral.

Streak

The ________ of a mineral is the color of its powder. You can see it by rubbing the mineral against a piece of rough tile. The ______ of a mineral may vary but its ______ does not. The _____ _____ and the _____ of the mineral are often different.

Cleavage

The arrangement of atoms in the mineral causes it to break apart more easily in one direction than another. If the mineral separates easily in only one direction than it has ___________.

How do minerals form by evaporation?

When the water in solutions evaporates it forms crystals/a mineral.

Inorganic

The mineral cannot form from materials that were once part of a living thing.

?

The mineral platinum is an element that often occurs as a pure metal. If a sample of platinum has a mass of 430 g and a volume of 20cm3, what is its density?

Crystal Systems

These can be classified into six groups: Cubic, hexagonal, tetragonal, orthorhombic, monoclinic and triclinic

Where do minerals form?

They can form on the surface through evaporation of solutions containing dissolved minerals. They can form beneath the surface when dissolved elements and compounds leave a hot water solution or when magma cools and hardens.

Hardness

This can be determined by a scratch test.

Hardness

This is one of the best clues you can use to identify a mineral.

Luster

This term is used to describe how light is reflected from the mineral's surface. Metals are often shiny. Quartz has a glassy ______. Other words commonly used to describe __________ are earthy, waxy, and pearly.

Describe the process by which a deposit of rock salt, or halite, could form from a solution.

Through evaporation of a solution.

How do minerals form from water solutions?

When elements and compounds that are dissolved in water leave a solution, crystallization occurs.

Mohs hardness scale

a ranking of minerals from softest to hardest

element

a substance composed of a single kind of atom

density

find mass per unit volume

streak

observe color of powder on unglazed tile

What size crystals form when magma cools rapidly?

small crystals

streak

the color of a mineral's powder

cleavage

the property of splitting evenly along flat surfaces

crystal

the repeating pattern of a mineral's particles in a solid

Naturally Occurring

the substance must be formed by processes in the natural world - not man made

Color

this is an easily observed physical property. Though alone it often does not provide enough information to make an identification. This property can only be used to identify those few minerals that always have their own characteristic ____________.