Rocks And Landform Project
Alex Breeden 7th Grade Cool Rays


Igneous rocks are formed by solidification of molten lava.

Basalt: Basalt is a fine grained, dark-colored rock. People use basalt for many purposes, crushed basalt is used for road base, concrete aggregate, railroad ballast, and lots of other things. When they are freshly made, they are dark black, but after weather changes the rock turns into a reddish, greenish, or blueish color.

Granite: Granite is a rock with grains visible with the naked eye, coarse grained, and its light-colored. Granite is mainly composed of quartz. The mineral composition of the rock gives granite a pink, red, grey, or white color and dark mineral grains throughout the rock. This is the best known igneous rock, its used to make countertops, floor tiles, paving stone, and more.

Obsidian: Obsidian is an igneous rock that forms when molten rock cools rapidly that atoms can't arrange themselves into a crystalline structure. The most common color of obsidian is black. It can be also be brown, green, or tan, but you rarely see obsidian in blue, pink, or red. Two colors of obsidian are swirled together, like brown and black, they are the two most common colors swirled together. Obsidian is a popular gemstone. Its hardness is a 5.5 which makes it easy to carve into.

Pumice: Pumice is a light-colored, extremely porous igneous rock. It forms during volcanic explosions. The holes in the rock are formed by gas bubbles that were once in the rock. The most common use of pumice rocks are using them in lightweight concrete blocks, and other lightweight concrete products.

Pegmatite: Pegmatite are extreme igneous rocks that form during the last stage of magma's crystallization. They are extreme because they contain large crystals, and they have minerals that are rarely found within them. They have a limited use as an architecture stone, it is rarely used in anything. The world's best gemstones are found in pegmatite.


Metamorphic rocks are rocks that were once a form of rock but changed to another under the influence of heat, pressure, or some other agents.

Slate: Slate is a fine-grained, foliated metamorphic rock that is caused by the alteration of shale. It is popular for its use for flooring, roofing, and flagging cause of it's durability and attractiveness. Mostly slates are gray and they come from light to dark grey. Slate also occurs in shades of green, red, black, purple and brown. The color of slate is mostly committed by the amount, type of iron, and organic material that are in the rock.

Marble: Marble is a metamorphic rock that forms when limestone is put through the heat and pressure of metamorphism. Marble is crushed and used as an aggregate in railroad beds, highways, and buildings. Marble is usually a light color and has the hardness of 3 on the Mohs hardness scale.

Soapstone: Soapstone is a metamorphic rock that is primarily composed of Talc. It is soft and easy to carve, it's heat resistant, and has high specific heat capacity. Soapstone is used in a variety of things that are used or are in the kitchen. For some examples are countertops, bowls, plates, sinks, electrical panels, wall tiles, and floor tiles.

Quartz: Quartz is a coarse grained, metamorphic rock. It can be either white, yellow, or brown. When you crack it open, it goes around the grains revealing a smooth surface. It can be used for buildings, walls, floor tiles, or roofing. It can be found in mountainous locations.

Gneiss: Gneiss is a coarse grained, foliated rock formed by regional metamorphism, its also metaphoric rock. The grains of Gneiss are elongated by pressure and the colors are usually light and dark bands. The lighter bands usually contain quartz.

Sedimentary Rock

Sedimentary rocks are types of rock that are formed by the deposition of material at the Earth's surface and within bodies of water.

Shale: Shale is a fine-grained sedimentary rock. Black shale has organic materials in it which makes gas. Other shales can be brushed and used for clay. The rock is laminated meaning that it is made out of different layers.

Sandstone: Sandstone is a sedimentary rock made out of sand sized grains. This is one of the most common sedimentary rocks there is. The particle size of the grains in the rock rather than the material of which it is composed is what sand means to the geologist.

Coal: Coal is an organic sedimentary rock that forms from the preservation of plants. Coal is used for heat, fuel, and oil. Those are the most common things which they use coal for.

Chert is a fine-grained silica-rich microcrystalline, cryptocrystalline or microfibrous sedimentary rock that may contain small fossils.

Limestone: Limestone is sedimentary rock composed of calcium carbonate. It mostly forms in clear waters. Limestone can also from from evaporation. Limestone is not found everywhere, people pay a lot more for limestone if it isn't found in a place near them.