Mineral and Rock Formation

• Minerals can form from cooled lava and magma after rocks melt due to extreme heat.
• The Earth's oceans contain elements that can combine to create minerals.
• Salt water solutions can create mineral precipitates like calcite, which is deposited in alkaline-rich water such as Mono Lake in Canada.
• Calcite tufa towers form when water bubbles up into alkaline lakes, and are revealed when lake levels drop.
• Underground water, heated by the Earth, can deposit minerals in cracks in the ground, forming veins.

Rocks

• The rock cycle involves the transformation of one type of rock into another.
• Rocks are naturally formed, non-living Earth materials composed of various minerals, sometimes too small to see.
• Rocks are named based on their mineral composition and how those minerals came together.
• Geologists study rocks.
• Igneous rocks form when magma cools, either on the Earth's surface or deep within the crust.
• Sedimentary rocks are created when sediments, such as gravel, sand, silt, or clay, are compacted together.
• Metamorphic rocks are formed when existing rocks are altered by heat and pressure, causing the minerals to change without melting.

Rock Cycle Process

• Rocks can form from processes such as volcanic eruptions or sediment compaction.
• Any type of rock can transform into another over extended periods.
• All three rock types (igneous, sedimentary, and metamorphic) are interconnected.
• Cooling and crystallization can change rocks
• Wind, erosion, ice, plants, and animals can all cause rocks to change and erode.
• Metamorphism occurs when rocks are exposed to high temperatures and pressures, but do not completely melt.
• Metamorphism can lead to new mineral compositions or textures in rocks.

Igneous Rocks

• Igneous rocks are abundant and constitute a significant portion of Earth's crust.
• The appearance of an igneous rock depends on the cooling rate and size of the magma.
• Sediments, such as sand, are fragments of rocks and minerals of varying sizes.
• Sediments must be tightly packed together to form sedimentary rocks.
• Sediments can contain fossils trapped in layers.
• Sediments can be transported by wind, water, ice, or gravity and are deposited in new locations.
• Sediments eventually settle out of water, forming horizontal layers.
• Rivers deposit sediment along their banks when they slow down.
• Clastic sediments are formed by compaction, while chemical sediments form when mineral crystals precipitate from saline or salt water.

Lithification of Sedimentary Rocks

• Sandstone is a rock formed through weathering and erosion.
• Clastic rocks are composed of sediments called clasts.
• Lithification is the process of creating rocks from sediments.
• Chemical sedimentary rocks form when chemicals precipitate from liquids.
• Over time, deposited sediments can harden into rocks through compaction and cementation.
• Compaction occurs when sediments are squeezed together by pressure and weight.
• Cementation involves minerals filling the spaces between loose sediment particles, originating from water moving through the sediment.
• Chemical sedimentary rocks form when crystals precipitate out of liquid, such as the formation of halite (rock salt) from evaporated salt water.
• Cementification occurs when mineral-rich water fills gaps between sediment particles.

Metamorphic Rocks

• Metamorphic rocks always start as another type of rock.
• During metamorphism, ions move in or out of a mineral, creating a different material that is more stable in the new environment.
• Extreme pressure can cause physical changes, such as foliation.
• Foliation is the layering of rock caused by pressure applied to one side.
• Rocks subjected to pressure from all sides usually show no foliation.
• Contact metamorphism occurs when magma comes into contact with a rock, and the magma's heat alters the rock without melting it.
• Regional metamorphism occurs over a wide area.
• Great masses of rock are exposed to pressure from overlying rock and sediment layers.
• Tectonic plate movements can also compress rock.
• Metamorphism does not completely melt the rock but causes mineral changes.
• If the rock melts, it will cool to become an igneous rock.
• Hornfels, displaying alternating colors of dark and light crystals, exemplifies how minerals rearrange themselves during metamorphosis.