Section 2.0 Rocks and Minerals

What are Rocks and Minerals?? Rocks are made of tiny particles called grains The appearance of these rocks depends on the nature of these grains and the materials they are made of. Minerals: building blocks of rocks which are pure, naturally occurring solid material You can have rocks made of 1 mineral (limestone) or rocks made of 2 or more minerals (granite)

5 Minerals = Earth’s Crust Calcite Quartz Feldspar Mica Hornblende

Properties to Identify Minerals Properties: features that a material or object has Complete the following definitions: Color Lustre Streak Cleavage Fracture Hardness

Identification of Minerals In 1812 the Mohs scale of mineral hardness was devised by the German mineralogist Frederich Mohs (1773-1839), who selected the ten minerals because they were common or readily available. This scale is a chart of relative hardness of the various minerals (1 - softest to 10 - hardest) Mohs' hardness is a measure of the relative hardness and resistance to scratching between minerals

Why is Hardness Important?? Diamonds are an important mineral component in cutting tools for the manufacturing of metals and other substances, forming dies for the drawing of wires, and for cutting cores in oil wells and mineral exploration Garnets were used as an abrasive in sandpaper Mineral harness is also important in sedimentary rocks. Harder minerals tend to be able to travel longer distances down river systems (ex. Quartz can often undergo several cycles of erosion)

2.2 Three Classes of Rocks: Igneous, Sedimentary, and Metamorphic

How are Rocks Formed?? Look at how minerals are arranged and the size of the grains Identify those formed by wind and water (sedimentary rocks), volcanoes (igneous rocks), and heat/pressure (metamorphic rocks)

Igneous Rocks Definition Igneous Rocks: “ignis” (latin meaning fire) form when molten lava (magma) cools and turn to solid rock There are 5 kinds of igneous rocks, depending on the mix of minerals in the rocks. Granite contains quartz, feldspar & mica Diorite contains feldspar & one or more dark mineral, feldspar is dominant. Gabbro contains feldspar & one or more dark mineral. The dark minerals are dominant. Periodotite contains iron and is black or dark. Pegmatite is a coarse-grained granite with large crystals of quartz, feldspar and mica.

Igneous Rocks Continued All igneous rock starts deep in the earth as hot, molten magma. If the magma cools and hardens inside the earth it is called "intrusive" rock. These rocks cool slowly and have large crystals. When the magma comes out of the earth's crust through a volcano, it is called "extrusive". It cools off quickly, and the crystals that form are very small. Molten, or hot, liquid rock is called MAGMA when it is still inside the earth, but once it comes out through a volcano it is called LAVA.

Sedimentary Rock Definition Sedimentary Rock: broken bits of the rock called “sediments” layer in streams and rivers Formed in four main ways deposition of the weathered remains of other rocks by the accumulation and the consolidation of sediments by the deposition of the results of biogenic activity; by precipitation from solution

Sedimentary Rocks Cont’d There are 6 main kinds of sedimentary rocks Conglomerate rock has rounded rocks (pebbles, boulders) cemented together in a matrix. Sandstone is a soft stone that is made when sand grains cement together. Shale is clay that has been hardened and turned into rock. It often breaks apart in large flat sections. Limestone is a rock that contains many fossils and is made of calcium carbonate &/or microscopic shells. Gypsum common salt or Epsom salt is found where sea water precipitates the salt as the water evaporates. Porphory rock is when jagged bits of rock are cemented together in a matrix.

Sedimentary rocks have fossils in them because plants & animals that have died get covered up by new layers of sediment and are turned into stone. Most of the fossils we find are of plants & animals that lived in the sea. They just settled to the bottom. Other plants & animals died in swamps, marshes or at the edge of lakes and were covered with sediments when the size of the lake got bigger.

When large amounts of plants are deposited in sedimentary rocks, then they turn into carbon, which gives us our coal, oil, natural gas and petroleum. A large sea once covered the central part of Canada and the climate was very tropical. In time, sedimentary rocks formed there. That is why we find dinosaur fossils in Alberta and the area is a good source of natural fuels. As water flows over and under the Earth’s surface, it will dissolve substances called “salts”, which explains why the ocean is salty; with rivers carrying so much of these salts into the ocean. Bodies of water have dried up therefore leaving salt beds behind.

Metamorphic Rocks Definition Metamorphic Rocks: comes from the Greek "meta" and "morph" which means to change form, rocks that have changed Originally igneous or sedimentary, but due to movement of the earth's crust, were changed Metamorphic rocks are igneous or sedimentary rocks that have been transformed by great heat or pressure.

Metamorphic Rocks Continued Two Types of Metamorphic Rocks: Foliated metamorphic: rocks that have layers, or are banded. Slate is transformed shale, It splits into smooth slabs. Schist is the most common metamorphic rock, Mica is the most common mineral Gneiss has a streaky look because of alternating layers of minerals 2. Non-foliated metamorphic: rocks are not layered. Marble is transformed limestone Quartzite is very hard

2.3 The Rock Cycle Rocks are constantly changing. The Rock Cycle does not have a set order as they are weathered, consolidated, buried, melted and solidified.

Investigating The Rock Cycle Soil formation is determined by climate, type of rock present, amount of water, organic material, air spaces and living organisms in the soil. It takes nearly 1000 years for 5mm of soil to form.

The Alberta Story: Investigating The Changing Earth The rocks that make up Alberta were laid down in layers over hundreds of millions of years ago. The oldest layer, the Precambrian Shield, is at the bottom. This layer is made up of igneous and metamorphic rocks that were formed between 544 and 4500 million years ago. This layer of rock covers all of Alberta, but is only exposed in the upper northeastern part of the province. 87% of the Alberta landscape lies over the Interior Plain, which is sandwiched between the Canadian Shield and the Rocky Mountains. The Interior Plain has various layers of sedimentary rock that are between 544 million and 1.5 million years old.

(where metamorphic rock is exposed) Dinosaur Provincial Park Pelican Rapids (where metamorphic rock is exposed) Dinosaur Provincial Park (where you can see sedimentary rock layers) Rocky Mountains (rocks that have been formed and changed)