Type of rock

Example Formation Features influencing weathering Common usage Location of major mine(region and country)

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Metamorphic

1. Marble Lime stone changed into a marble by pressure and heat changing.

It depends on the type of minerals in the rock but they will weather unevenly. It usually weathers when it is exposed to the rain.

Floor and sculpture

Georgia

2. Hornfels

Metamorphism where magma breaks the rock into new rock.

The rock weathers layer by layer depending on the mineral composition of that layer.

Part of material used in construction and roading industries.

Australia, India and France

Igneous 1. Basalt Magma reaches the Earth’s surface as lava. As it cools rapidly, it creates small crystals.

Basalts weather relatively fast. Chemical weathering. Basalt itself is often associated with the release of large quantities of carbon dioxide into the atmosphere from volcanic gases.

It is crushed and used to make many types of flooring products such as tiles and cobblestones. It is also mixed with asphalt or concrete for paving.

• Deccan Traps in India

• Chilcotin Group in British Columbia

• Canada• Siberian

Traps in Russia

2. Andesite

Fractional crystallization at convergent plate margins.

Andesite is mostly made up of the minerals (plagioclase, pyroxene, feldspar and hornblende). Andesite usually has a lighter grey color than basalt. So andesite will darken with weathering.

Tile and bricks especially for gardens.

Boulder Country, Colorado

Sedimentary

1. Sandstone

Grains of sand being compressed and cemented together.

Sandstone has several different forms of weathering, which wear it down over time. Ice Crystallization – water seeps into a pore or crack in sandstone and then freezes. It has the potential to fracture sandstone and break pieces off.Salt Crystallization – saline solution that enters a crack in the sandstone and then crystallizes and expands. (Often, ice crystallization and salt crystallization work together to weather sandstone. )Expansion and Contraction – constant cycles of expansion and contraction can also weaken sandstone over time and eventually cause it to break apart. The molecules (of expansion and contraction) in sandstone occur when it heats and cools and when it is wet and then dries. Lichens – lichens grown on rock and they produce a chemical that breaks down stone. Lichens will eventually make cracks and holes in sandstone.

The more holes, pores or cracks there are in a piece of sandstone, the more susceptible to weathering.

Building materials, and can produce a fertile soil.

Deserts or dry places like the Sahara Desert in Africa. The Arabian desert in the Middle East and the Australian desert (including Sydney).

2. Shale It starts out as clay and then erosion moves it from place to place. It falls into streams and forms a layer. The clay hardens by being heated and pressured down and forms layer of shale.

It depends upon how much pyrite (iron sulfide) is present in the shale. More pyrites will help to chemically weather the shale. Certain bacteria may also help to speed up the process of pyrite oxidation.

Shale is used in cement and bricks, concrete, and road construction, and ceramic products.

It is mined in the western United States.