It's a ROCKY Life Learning so much about the life of Rocks from Mr. Piner


Rocks are classified into 3 groups, one of them being Sedimentary. Sedimentary rocks are formed from deposition and cementation of material at the Earth's surface and within bodies of water. There are 3 ways sedimentary form; Inorganic, Chemical, and Organic.



It is composed of mainly of silt-sized particles and forms where water, wind, or ice deposit silt, and the silt. Then it is compacted and cemented into a rock.



It is composed of calcium carbonate and it is most commonly formed in clear, warm, shallow marine waters. It is considered to be a chemical sedimentary rock formed by the precipitation of calcium carbonate from lake or ocean water.



It can be considered Bituminous Coal is a soft coal that contains a tarlike substance called bitumen. It has a higher quality than lignite coal, but poorer quality than anthracite. Its formation is usually the result of a high pressure being exerted on lignite.


Igneous rocks are known as fire-formed rocks that form from molten rock such as, lava and magma and solidifies intrusively and extrusively.


Granite is a light-colored rock containing large grains. It forms from the slow crystallization of magma below Earth's surface.


Pumice is a light-colored, extremely porous igneous rock. It forms during explosive volcanic eruptions.


Rhyolite is an extrusive igneous rock. It is made up of quartz, plagioclase, and sanidine, with minor amounts of hornblende and biotite. These often contain crystals, opal, or glassy material.


Metamorphic rocks are modified by heat, pressure, and chemical processes, all while buried deep below the Earth's surface. Exposure to these extreme conditions has altered the mineralogy, texture, and chemical composition of the rocks.


Gneiss is a foliated metamorphic rock. It is identified by its bands and lenses of varying composition, while other bands contain granular minerals with an interlocking texture.


Marble is formed when limestone is subjected to heat and pressure of metamorphism. It is composed primarily of the mineral calcite and usually contains other minerals, such as clay minerals, micas, quartz, pyrite, iron oxides, and graphite. Under the conditions of metamorphism, the calcite in the limestone recrystallizes to form a rock that is a mass of interlocking calcite crystals.


Slate is a fine-grained, foliated metamorphic rock that is created by the alteration of shale or mudstone.



  • A Streak Plate is used for the "streak test". A method used to determine the color of a mineral in powdered form. The color of a mineral's powder is very important for identifying the mineral.
  • Magnifying Glasses are used to look close to identify what the rock contains. Or if it doesn't contain anything.
  • A Hardness Kit is a kit full of materials that determines the hardness of an unknown rock or mineral.
  • Your fingernail has a hardenss of 2.5. If you can scratch the surface of an unknown specimen with it, you will immediately know that its hardness is less than 2.5. In other words, it is slightly harder than gypsum, but softer than calcite.
  • A copper penny has a hardness of 3.0 - slightly harder than your fingernail. So, if you can't scratch the specimen with your fingernail, but a penny does the job, you immediately know that it is at least as hard as calcite.
  • A steel blade usually has a hardness of about 5.5. If a penny does not scratch your unknown specimen but the blade does, then you can correctly conclude that it is harder than calcite, but softer than orthoclase.
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