Eric Angat Environmental Science Rocks contain Minerals
All rocks contain one or more minerals.
Minerals are formed when elements bond together.
Gemstones are valuable minerals that can be used to make jewelries.
Salt is one of the most common minerals. We use it for preparing our food and many other uses.
Copper is another common mineral. It is used for electrical wirings.
A rock can contain more than one type of mineral.
Granite contains two minerals. They are feldspar and quartz.
Rocks are identified based on: 1. Ingredients ( type of minerals present) 2. How they formed.
Melted and hardened are igneous. Weathered and eroded into tiny fragments and then cemented together are sedimentary. Buried and exposed to extreme heat and pressure are metamorphic.
Geologist explain how rock are formed and destroyed by using the rock cycle.
Igneous rocks are fire formed.
Cooled and hardened molten magma form intrusive igneous rocks.
Cooled and hardened lava form extrusive igneous rocks
Metamorphic rocks are “changed” rocks. Due to extreme heat and pressure, an igneous rock can become a metamorphic rock like granite to schist. And a shale, a sedimentary rock, can become slate, a metamorphic rock.
Sedimentary rocks are small rock fragments joined together by pressure. The small rock fragments can contain pieces of igneous and metamorphic rocks.
Rocks form beneath the ground, except for extrusive igneous rocks. One way for rocks to get exposed is through weathering and erosion.
In sedimentary rocks, the oldest is always the one at the bottom because that layer is the first one that formed.
Fossils are the remains of plants and animals trapped or imprinted on sedimentary rocks.
Fossils are not found in igneous and metamorphic rocks because any plant and animal remain trapped in both rocks is burnt off due to extreme heat.
Igneous rocks are formed from the solidification of molten rock material.
There are two basic types: 1)intrusive igneous rocks such as diorite, gabbro, granite and pegmatite that solidify below Earth's surface. 2)extrusive igneous rocks such as andesite, basalt, obsidian, pumice, rhyolite and scoria that solidify on or above Earth's surface.
Intrusive igneous rocks such as diorite, gabbro, granite and pegmatite that solidify below Earth's surface.
extrusive igneous rocks such as andesite, basalt, obsidian, pumice, rhyolite and scoria that solidify on or above Earth's surface.
Porphyritic is a type of igneous rock that has a distinct difference in the size of the crystals, with at least one group of crystals obviously larger than another group.
Andesite This is an extrusive porphyritic rock, as the pink (and black) phenocrysts are clearly visible, in contrast the grey groundmass with its microscopic crystals.
Aphanitic fine-grained basalt
Gabbro better developed crystals
This granite has coarse-grained indicating that the crystals had a much longer time to crystallize
Medium-grained granite. The size of the crystals indicates that it took longer to cool than the fine-grained granite
If the magma forming an igneous rocks fragments, or cools quickly and explosively, it may produce pumice, a pyroclastic rock.
Pumice is very porous and will sometimes float on water.
Metamorphic rocks have been modified by heat, pressure and chemical process usually while buried deep below Earth's surface.
There are two basic types of metamorphic rocks: 1)foliated metamorphic rocks such as gneiss, phyllite, schist and slate which have a layered or banded appearance that is produced by exposure to heat and directed pressure. 2) non-foliated metamorphic rocks such as marble and quartzite which do not have a layered or banded appearance.
Foliated metamorphic rocks such as gneiss, phyllite, schist and slate which have a layered or banded appearance that is produced by exposure to heat and directed pressure.
Non-foliated metamorphic rocks such as marble and quartzite which do not have a layered or banded appearance.
Metamorphism Any type of rock – igneous, sedimentary, or metamorphic rocks can become a metamorphic rock.
Foliated Metamorphic Rock
Quartzite is a non-foliated metamorphic rock that is produced by the metamorphism of sandstone.
Quartzite is very hard and is often crushed and used in building railroad tracks
Schist is metamorphic rock with well developed foliation. It often contains significant amounts of mica which allow the rock to split into thin pieces. chlorite schist
Schist is metamorphic rock with well developed foliation. It often contains significant amounts of mica which allow the rock to split into thin pieces. muscovite schist
Schist is metamorphic rock with well developed foliation. It often contains significant amounts of mica which allow the rock to split into thin pieces. garnet schist
Slate is a foliated metamorphic rock that is formed through the metamorphism of shale. It is a low grade metamorphic rock that splits into thin pieces.
Schist and slate are sometimes used as building and landscape materials.
Graphite, the “lead” in pencils, is a mineral commonly found in metamorphic rocks.
Marble is a non-foliated metamorphic rock that is produced from the metamorphism of limestone.
Marble, a metamorphic rock, is used for decorative items and in art.
Amphibolite is a non-foliated metamorphic rock.
Gneiss is foliated metamorphic rock that has a banded appearance and is made up of granular mineral grains.
Sedimentary rocks are formed by the accumulation of sediments.
Three basic types of sedimentary rocks: 1) clastic sedimentary rocks such as breccia, conglomerate, sandstone and shale, that are formed from mechanical weathering debris 2) chemical sedimentary rocks such as rock salt and some limestones, that form when dissolved materials precipitate from solution.form 3) organic sedimentary rocks such as coal and some limestones which form from the accumulation of plant or animal debris.
Clastic sedimentary rocks such as breccia, conglomerate, sandstone and shale, that are formed from mechanical weathering debris
Chemical sedimentary rocks such as rock salt and some limestones, that form when dissolved materials precipitate from solution.
Organic sedimentary rocks such as coal and some limestones which form from the accumulation of plant or animal debris.
Breccia is a clastic sedimentary rock that is composed of large (over two millimeter diameter) angular fragments.
Chert is a microcrystalline or cryptocrystalline sedimentary rock material composed of silicon dioxide (SiO 2 ). It occurs as nodules and concretionary masses and less frequently as a layered deposit.
Coal is an organic sedimentary rock that forms mainly from plant debris. The plant debris usually accumulates in a swamp environment. Coal is combustible and is often mined for use as a fuel.
Conglomerate is a clastic sedimentary rock that contains large (greater then two millimeters in diameter) rounded particles. The space between the pebbles is generally filled with smaller particles and/or a chemical cement that binds the rock together.
Iron Ore is a chemical sedimentary rock that forms when iron and oxygen (and sometimes other substances) combine in solution and deposit as a sediment. Hematite (shown above) is the most common sedimentary iron ore mineral.
Limestone is a rock that is composed primarily of calcium carbonate. It can form organically from the accumulation of shell, coral, algal and fecal debris.
Rock Salt is a chemical sedimentary rock that forms from the evaporation of ocean or saline lake waters. It is also known by the mineral name "halite".
Sandstone is a clastic sedimentary rock made up mainly of sand-size weathering debris. Environments where large amounts of sand can accumulate include beaches, deserts, flood plains and deltas.
Shale is a clastic sedimentary rock that is made up of clay-size weathering debris. It typically breaks into thin flat pieces.
Siltstone is a clastic sedimentary rock that forms from silt-size weathering debris.