Mineralogy: The Study of Minerals and their Properties A Mineral! Occurs! Is a! Is a substance (element or compound)! Has atoms arrange in an orderly pattern ( )! Is (not formed by any process involving plants or animals) The most common elements that make up minerals are oxygen, silicon, aluminum, iron, calcium, potassium, and magnesium There are over known minerals; most are. Common minerals that make up most of the Earth s crust are called - MINERALS Most minerals are (i.e., halite = NaCl, Galena = PbS) A few minerals are made up of only ONE element, and are called elements (i.e., gold, copper, silver, sulphur, carbon)
Mineral Identification Minerals are usually identified using properties, although some simple tests may also be used. IDENTIFICATION BY INSPECTION: Colour First, and most easily property Some minerals have colours (i.e., malachite, sulphur) However, many different minerals have colours may also alter the colour of minerals Lustre The way a mineral shines in light. Either metallic (like polished ) or non-metallic Non-metallic lustre may be further described as (glass-like), pearly, greasy, dull, earthy, etc. Crystal Shape When minerals have time and room to form, their particles arrange themselves into flat-faced, regularly shaped. However, most mineral grains are too small or imperfect to identify.
IDENTIFICATION BY SIMPLE TESTS Streak The colour of a mineral s when it is rubbed against a streak plate Metallic minerals give streaks (brown, grey, black) Nonmetallic minerals give streaks Cleavage/Fracture A mineral exhibits cleavage if it breaks along flat when hit with a hammer. A mineral exhibits fracture if it splits into or surfaces. Hardness A mineral s to being scratched. Moh s hardness scale: measure of how hard a mineral is compared to a set of minerals, ranging on a scale from 1 to 10 (softest = talc (1), hardest = diamond (10)). Prospector s Scale: Fingernail = 2.5 Penny = 3 Steel = 5.5 Glass = 6
Specific Gravity The relative of a mineral. Ratio of mineral s weight to an equivalent amount of. Specific gravity of minerals is generally < 3 Specific gravity of minerals is generally > 5 Acid Test When calcite is exposed to, it fizzes Gas produced is dioxide Magnetism Some minerals containing iron are and will be attracted to a magnet (ie., magnetite) OTHER PROPERTIES: Taste (i.e., rock salt) Fluorescence (glows in light) Radioactivity Double
Mineral Groups All minerals can be classified as either or minerals Silicates Silicate minerals contain atoms of (Si) and (O) Some only contain silicon and oxygen (i.e., ), but most also contain one or more other (i.e., feldspar) is the most common mineral in the earth s crust, followed by Silicates make up % of the Earth s crust Non-silicates 4% of the Earth s crust is made up of non-silicate minerals (meaning they don t contain ) Can be further classified as: o Carbonates contain carbonate (CO 3 ) group o Halides halogens (Cl, F) with Na, K or Ca o Native o Oxides contain, but not silicon o contain sulphate ( (SO 4 ) group o Sulfides contain
PETROLOGY The Study of Rocks and their Formation PRINCIPLES OF UNIFORMITARIANISM: 1. Geological processes now at work were also active in the. 2. Physical features of the Earth were formed by these processes over periods of time. In other words, the rocks we see around us were formed in the past by the geological processes we see around us today. Rock Types and the Rock Cycle A rock is a of minerals bound together (i.e., it is usually a ). There are three types of rock: 1. igneous rock formed when rock cools 2. sedimentary rock formed from weathered and eroded rock that is and together into new rock. 3. metamorphic rock formed when existing rock undergoes intense and that alters the rock s composition and characteristics.
IGNEOUS ROCKS comes from the Greek word for fire. Deep inside the earth, the temperature is very high and the rock there is in liquid form called. As magma pushes towards the Earth s, it starts to cool and turn into solid igneous rock. Igneous rocks that cool deep in the Earth are called intrusive or plutonic igneous rocks. Other igneous rocks form when magma erupts from a volcano, or reaches the surface through long cracks in the crust. Magma is called when it reaches the Earth s surface. These are called extrusive or volcanic igneous rocks. Igneous rocks are classified by (the minerals it contains) and (crystal size).
Composition of Igneous Rocks Igneous rocks form from two main types of magma: FELSIC:! Magma with a percentage of silica (SiO 2 ) and little calcium, magnesium or iron.! Felsic magma is and slow-flowing! Forms -coloured rocks! Most rocks are felsic MAFIC:! Magma with a silica content, with higher amounts of calcium, magnesium and iron.! Hotter and than felsic magma! Forms -coloured rocks! Most rocks are mafic
Texture of Igneous Rocks Depends on of mineral crystals in the rock. Crystal size depends on how magma hardens LONGER = LARGER Plutonic rocks cool slower, therefore grains Lava hardens rapidly forming crystals Lava that cools super-quick forms rocks with crystals Porphyry: a rock with 2 stages of cooling, so that it has both and crystals.
SEDIMENTARY ROCKS most of the earth s is covered in sedimentary rocks there are three types of sedimentary rocks: a. clastic - made from of other rocks. b. chemical - formed from precipitates falling out of. c. organic - formed from remains of and. Clastic Sedimentary Rocks form when rocks (break apart). That material is eroded ( away) and later in another location. Layers of sediment undergo and to eventually form sedimentary rocks. Clastic rocks are classified by (size of particles) " Conglomerate: made up of and sand " Sandstone: mainly of quartz " Shale: tiny flakes of cemented together Chemical Sedimentary Rocks Form when sea, lake, swamp or underground waters or change temperature, causing dissolved minerals to fall out of solution. Examples include some, rock salt and rock gypsum.
Organic Sedimentary Rocks Formed from the of plants and animals Shell-producing organisms such as clams, mussels or coral are made up mostly of the mineral that makes up limestone. When they die their shells pile up on the floor of the water body, and eventually together to form limestone. Coal is formed from plants that are buried and compacted into matter that is mostly.
Metamorphic Rocks and can cause certain minerals to change into other minerals. Mineral crystals may also change in or, and may separate into bands. Hot may circulate through a rock, dissolving some minerals and depositing others. Types of Metamorphism: 1. Contact metamorphism when hot magma pushes through rock, causing changes in the structure and composition of surrounding rock. 2. Regional metamorphism movement of tectonic plates creates tremendous and at plate boundaries, changing minerals into rock.
Classification of Metamorphic Rocks: Made according to the texture of the rock (foliated or non-foliated), and the composition of the rock. FOLIATED: o Extreme pressure mineral crystals in rock and pushes them into parallel bands o Minerals of different separate into bands, often producing alternating dark and light layers. o Examples included slate, schist and gneiss NON-FOLIATED: o No banding or are observed o Examples include quartzite and marble o
Rock Cycle