2 The next few chapters in geology are mostly about rocks The next few chapters in geology are mostly about rocks. Nearly all rocks are made of minerals, so in order to learn about rocks you need to know something about minerals. In Chapter 5, you will discover that:Each mineral is made up of specific chemical elements, the atoms of which are organized in a special arrangement.The chemical makeup and its internal structure determine an element’s physical properties.3. A mineral can be identified by its physical characteristics, such as: cleavage, crystal form, fracture, hardness, lustre, colour, streak, and specific gravity.
3 What is Matter?Matter – the substance of which any physical object is composed. Everything is made of matter.States of Matter:SolidLiquidGasControlling factors:TemperaturePressureExamples: Gold Mercury Oxygensolid liquid gas
4 The stuff that makes up all matter The make-up of solid matter on Earth:Atoms Elements Compounds Minerals Rocks(smallest) (largest)What is an atom?An atom is the smallest particle of a matter that keeps the properties of that matter. For example, all sodium atoms are essentially identical to all other sodium atoms. Water (H2O) can be broken down into two atoms of hydrogen (H) and one atom of oxygen (O).
5 What are elements?Elements are the fundamental building blocks of matter. Elements cannot be broken down into smaller units. Elements are pure substances and are made of one or more of the same type of atoms. All elements are listed in the periodic table of the elements.
7 Element abundances in the crust All others: 1.5%
8 What are the most abundant elements in the Earth’s crust? Oxygen (O)-Oxygen is the most abundant element in the crust (makes up about 50% of the crust)-Oxygen bonds easily with other elements
9 Silicon (Si)-Most silicon form bonds with oxygen to form silica-Quartz (SiO2) is pure silica that has been crystalized-Any mineral that contains silica is called a silicate
10 Aluminum (Al)-Aluminum is more common that iron, but difficult to separate from rocks because it binds very tightly with oxygen.Other elements in the Top 8 include:Iron PotassiumCalcium MagnesiumSodium
12 Mineral characteristics Definition of a Mineral:naturally occurringinorganicsolidcharacteristic crystalline structuredefinite chemical compositionQUIZ!!!steel plastic sugar table salt mercury ice coalno, #1no, #1no, #1,2YES!no, #3YES!no, #2basalt obsidian mica gold paper chalk coralno, #5no, #4YES!YES!no, #1,2no, #2no, #2
13 Mineral characteristics Naturally formedNo substance created artificially is a mineral.examples: plastic, steel, sugar, paperInorganicAnything formed by a living organism and containing organic materials is not a mineral.examples: wood, plants, shells, coalSolidLiquids and gases are not minerals.examples: water, petroleum, lava, oxygen
14 Mineral characteristics Characteristic crystalline structuremust have an ordered arrangement of atomsdisplays repetitive geometric patterns in 3-Dglass not a mineral (no internal crystalline structure)Definite chemical compositionmust have consistent chemical formulaexamples: gold (Au), quartz (SiO2), orthoclase (KAlSi3O8)basalt (like many other rocks) contains variable ratios of different minerals; thus, has no consistent formula
15 How many minerals are there? Nearly 4,000 types of mineralsOnly ~30 occur commonly (whew!)Why not more?Some combinations are chemically impossibleRelative abundances of elements don’t allow more
16 SilicatesMost minerals are silicates (which means they contain silicon & oxygen)Silicates have a very special structure called a tetrahedron. This tetrahedron is the building block of a the silicate crystals
17 Silicate tetrahedrons can combine together to make much bigger structures. Diamond is NOT a silicate,but pure crystallized carbon.It is a very strong tetrahedron(and also a mineral).
18 Minerals of the Earth’s Crust The following are silicate minerals. They are the most common minerals and make up about 90% of the crust.FeldsparsQuartzPyroxenesAmphibolesMicas