Minerals

MINERALSWHAT ARE MINERALS AND HOW DO THEY FORM?

MATTER AND MINERALS

1. An atom is the smallest part of an element that retains the elements' properties.

2. Compounds are substances that are made up of two or more elements that are chemically bonded as molecules.

3. Minerals are solids and are composed of elements.

WHAT DO MINERALS HAVE IN COMMON?

• A mineral is a naturally occurring, inorganic solid that has a definite crystalline structure and chemical composition.• Minerals are grouped according to the shape of

their chystals.

EXAMPLES OF MINERALSTHE MINERAL AMETHYST-

Chemical Formula SiO2

Composition : Silicon dioxide. Its purple coloring is usually caused by impurities of iron or manganese compounds.Color Light to dark purple. Sometimes banded with purple and whitish lines. May also be mixed together with Citrine.StreakWhiteHardness 7

INORGANIC AND NATURALLY OCCURRING

• AN inorganic substance is not made up of living things or the remains of living things.

• Minerals are formed by many different natural processes that occur on Earth and throughout the universe.

• Talc – used in baby powered: is formed deep in Earth as high temperature and pressure change the rock.

CRYSTALLINE STRUCTURE

Minerals are composed of crystals:

A crystal is a sold, geometric form that results from a repeating patter of atoms or molecules. Turn to page 142 and 143 in textbook.

CRYSTALS SHAPE

• A crystals shape is produced by the arrangement of the atoms or the molecules within the crystal. The arrangement is determined by the kinds of atoms or molecules that make up the mineral.

MINERALS CAN FORM THREE WAYS

• 1. Magma and lava cooling• 2.Metamorphism• 3. From Solutions

MINERALS FORMED FROM MAGMA OR LAVE

• Magma and lava contains atoms present in minerals, when magma and lava cool quickly and solidify small crystals form.• When cooled slowly large crystals are formed• What is the difference between magma and lava?

QUARTZ

Quarts is one of the minerals that crystallize from magma and lava.

MINERALS FORMED FROM COOLING MAGMA OR LAVA

• Topaz:

Magma that cools forms Pegmatites . Crystals in Pegmatites are found in Topaz.

METAMORPHISM

• Temperature and pressure can cause atoms to break bonds with other atoms creating new minerals.

METAMORPHISMGraphite composed entirely of carbon atoms transfers into a diamond under head and pressure.

SOLUTIONS

• Minerals form from solutions by the water evaporating. As water evaporates, the substances form into a solid.• Ex: gypsum forms as water evaporates: the mineral

gypsum is left after water evaporate hardens and gypsum is formed.

HOW MINERALS ARE CLASSIFIED

• Based on chemical composition• Divided into two groups: Silicate minerals and nonsilicate minerals

SILICATE MINERALS

• Silicate minerals make up 90% of the Earth’s crust.• Minerals with silicon and oxygen are called silicate

minerals.• Silicates are made up of repeating tetrahedron shaped

units.

Feldspar Quartz

SILICON TETRAHEDRONS

One Silicate tetrahedrons are made of one silicon atom bonded into four oxygen atomsMost silicate minerals are composed of silicate tetrahedrons combined with other elements like aluminum pg. 146

NONSILICATE MINERALS

• Do not contain silicate tetrahedron building block• These minerals are made up of elements : carbon, oxygen,

fluorine, iron and sulfur.

PROSPERITIES TO IDENTIFY MINERALS

• Color – Color can be used to identify a mineral.• Streak – the mark left by the mineral on a white tile is the mineral’s

streak. Streak is more reliable in detecting a mineral than its color. • Luster- When the mineral gives off a shine. Two types of luster metallic

and nonmetallic• Cleavage: has a smooth surface and parallel cracks running through the

mineral. Book pg. 149• Fracture: uneven breaks throughout the mineral.

PROPERTIES TO IDENTIFY MINERALS

• Density – how much matter in the substance. The density of the mineral pyrite can distinguish it form gold.

• Hardness – a mineral’s resistance to being scratched is its harness. Scientists use Mohs scale to rate the minerals degree of hardness. Pg. 150

• If the reference mineral scratches your mineral, the reference mineral is as hard or harder than your mineral. What is the hardest known mineral and only the same mineral can scratch it?