Open your books to page 30 Please take notes over the yellow slides!

 We use products made from minerals everyday such as ceramics, metals, and even some paper items are made from minerals. As a matter of fact, the pencil you write with each day is made from the mineral graphite.  See figure 1 on page 30. Can you identify what objects are made of minerals?  Minerals are the building blocks of all rocks. There are about 4,000 minerals that have been identified.

 Minerals - A naturally occurring, inorganic solid with a definite chemical composition and an orderly arrangement of atoms

There are four characteristics of minerals:  Naturally occurring – made by nature (no help from humans).  Inorganic –they aren’t made by life processes

 Definite chemical composition – made of one or more elements (see periodic table of elements in back of book).  There are actually eight elements that make up most minerals. They are oxygen, silicon, aluminum, iron, calcium, sodium, potassium, and magnesium. These elements make up about 98% of Earth’s crust.  SO…elements are the building blocks of minerals and minerals are the building blocks of rocks.

 Orderly arrangement of atoms – this means they have a solid, crystalline structure.  Crystalline means that the atoms are arranged in a pattern that is repeated over and over again. For example, graphite atoms are arranged in layers, but an opal (gemstone) is not a mineral because the pattern does not repeat.  Gases (and water) are not minerals. Minerals must have a definite shape. Only solids can be minerals.

Minerals are the building blocks of all rocks. What is a mineral? Naturally occurring - made by nature Inorganic - they aren’t made by life process Definite chemical composition – made of one of more elements. Orderly arrangement of atoms - this means they have a solid, crystalline structure.

 Crystal – a solid where the atoms are arranged in an orderly, repeated pattern.  Remember – minerals have a crystalline structure.  You can see evidence of atoms arranged in an orderly pattern when you look at certain types of crystals. (Exp: geode)

 Rose Quartz does not look orderly on the outside, but the crystal structure on the inside is orderly and arranged as a crystal structure.  The crystal shape is not as definite because the rose quartz developed in a tight space and the geode developed in an open space.

 There are six major crystal systems. Minerals are often classified by their crystal structure. (See pg. 32 for a list of structures)  Crystals can form by many different processes. We will learn about two of those processes…crystals that form from magma and crystals that form from solutions of salts.

Cubic Triclinic Monoclinic Orthorhombic TetragonalHexagonal

Structure of Minerals Crystal Structure – a solid where atoms are arranged in an orderly, repeated pattern There are 6 major crystal systems

 Magma is hot melted rock below the Earth’s surface.  This magma cools as it reaches Earth’s surface, or even if it’s trapped below the surface.  As the magma cools, the atoms lose heat energy, move closer together, and begin to combine into compounds.

 During this process, atoms from the different compounds begin to arrange themselves into orderly, repeating patterns.  The type and amount of elements present in the magma partly determine which minerals will form.

 Also, the size of the crystals that form depends partly on how rapidly the magma cools.  When magma cools slowly, the crystals are large. This is because the atoms have time to move together and form larger crystals before the cooling process ends.  When magma cools quickly, the crystals are small. There is not enough time from large crystals to form so they remain small.

 Crystals can form from solutions as water evaporates or if too much of a substance is dissolved in water. (See picture of salt deposits on pg. 33. figure 4).

Crystals Form in Many Different Processes Crystals can form from hot magma. When magma cools slowly, the crystals are large. When magma cools quickly, the crystals are small Crystals can form from a solution. Happens when water evaporates or if too much of a substance is dissolved in water.

 90 elements occur naturally in Earth’s crust.  Approx. 98% of the Earth’s crust is made up of 8 out of the 90 known elements.  These 8 elements are oxygen, silicon, aluminum, iron, calcium, sodium, potassium, magnesium  Of the thousands of known minerals, only a few dozen are common and are composed mainly of the eight most common elements found in Earth’s crust.

 Silicates – the most common rock forming mineral group  They contain silicon and oxygen, and usually one or more other elements.  Silicon and oxygen are the two most abundant elements found in Earth’s crust.  These two elements alone combine to form the basic building blocks of most minerals in the Earth’s crust.  Most minerals are composed from silicone and oxygen and combined with other elements

Minerals Compositions and Groups 90 elements occur naturally in Earth’s crust 98% of Earth’s Crust is made up of 8 out of 90 elements. Silicates – the most common rock forming mineral group.  They contain both silicon and oxygen.  Most minerals are composed from silicone and oxygen.