Narrative Ojt

ROCKS

Rock- is a solid aggregate of one or more minerals.

Petrology- the study of rock

Most rocks are composed of silicate minerals, Granite, for example, is a rock that is made up of three silicate minerals: quartz, mica and feldspar. Rocks are classified in several ways: by their origin, mineral, composition, texture and color.

Rocks are classified into 3 major types based upon the way they originated.

Igneous Rock

Igneous rock-the word igneous comes from the Latin ignis, which means “fire”.

Formed when molten magma may cool and crystallize to solid igneous rock either below or on the surface of the earth

2 main category

Intrusive igneous rock (Plutonic)- magma that cools slowly deep below the surface of the earth

Ex. Granite

Extrusive igneous rock (Volcanic)- lava that cools rapidly above the surface

Ex. Pumice, basalt

Sedimentary Rock

For thousands, even millions of years, little pieces of our earth have been eroded- broken down and worn away by wind and water to form sedimentary rocks.

The weathered materials are transported by moving water, wind, ice and deposited as sediments- are accumulations of silt, sand and gravel the settle out of the atmosphere or out of water.

2 sources of sediments

1. Weathered rock fragments are called clastic sediments

Weathered rock fragments- Ex. of sedimentary socks are formed from clastic sediments are conglomerate, sandstone, siltstone and clay stone.

When deposited from the air clay and silts sized particles are called “dust”.

2. Dissolved rock materials from chemical sediments that are removed from solution to form sedimentary rock. The dissolved materials are ions from minerals and rocks that have been completely broken f 3 path.

      Chemical precipitation from solution

      Crystallization from evaporating water

      Biological sediment

The most abundant chemical sedimentary rocks are the carbonates and evaporates. The carbonates are limestone and... [continues]

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