Rock Classifications What are the three main types of rocks? Igneous Sedimentary Metamorphic
Igneous Rocks Can be a single mineral or an aggregate of many minerals Created by volcanic activity Can form on earth’s surface or below it Oldest Rocks on earth
Minerals Composed of one substance Can be a single element Examples: Halite (salt) Sulfur Quartz Calcite
Igneous Rocks Cont.Coarse Grain Rocks Intrusive – Formed inside the earths surface Cooled slowly Large crystals – Slow cooling allowed the crystal forming minerals more time to collect Examples: Granite Gabbro
Igneous Rocks Cont.Fine Grain Rocks Formed at earths surface – above ground or under water Cooled very quickly Examples: Basalt Rhyolite Obsidian – volcanic glass no crystals due to instant cooling
Sedimentary Rocks Not formed from volcanic activity Made of other rocks and minerals Grain size can range from not present to huge boulders Pieces that make up a sedimentary rock are called sediments.
Sedimentary Rocks The two types of sedimentary rocks are: Clastic Non-Clastic
Clastic Sedimentary Rocks Made up of rock fragments, shells, or other sediments cemented together Can often see or feel the different sediments in the rock Examples Sandstone Conglomerate Breccia
Non-Clastic Sedimentary rocks Usually made of one chemical Can be composed of: Precipitated minerals in water Once living plants or organisms Examples: Coal Gypsum Limestone
Metamorphic Rocks Rocks that have undergone change due to extreme heat and pressure The rocks and minerals contained in them do not melt during this process.
Metamorphic Rocks There are two main types of metamorphic rocks, what are they? Stratified Non-stratified
Stratified Rocks Rocks that have visible bands of minerals Bands run in lines that resemble layering Has had extreme pressure applied to two opposite sides The bands are minerals that grouped together during the extreme pressure
Examples of Stratified RocksParent Rock Metamorphosed Rock Granite Gneiss by Andrew Alden by Andrew Alden Shale Schist by Andrew Alden by Andrew Alden
Non-stratified Rocks No rings or bands Noticeable change from parent rock Pressure was applied from all directions Parent Rock Metamorphosed Rock •Limestone •Marble •Photo by: Georges Grondin Photo by: Titus Tscharntke