When a rock is exposed to extreme heat and pressure within the Earth but does not melt, the rock becomes metamorphosed. Metamorphism may change the mineral composition and the texture of the rock. For that reason, a metamorphic rock may have a new mineral composition and/or texture.

The most important agents of metamorphism include temperature, pressure, and fluids.

There are three ways that metamorphic rocks can form. The three types of metamorphism are Contact, Regional, and Dynamic metamorphism. Contact Metamorphism occurs when magma comes in contact with an already existing body of rock.

Heat that results in metamorphism is the result igneous intrusions and from deep burial. The two most important sources of heat for metamorphism are: A) intrusive magma bodies and deep burial.

Contact metamorphism occurs to solid rock next to an igneous intrusion and is caused by the heat from the nearby body of magma.

Metamorphic Rocks

Metamorphic rocks form when heat and pressure transform an existing rock into a new rock. Contact metamorphism occurs when hot magma transforms rock that it contacts. Regional metamorphism transforms large areas of existing rocks under the tremendous heat and pressure created by tectonic forces.

Most changes happen very slowly; many take place below the Earth’s surface, so we may not even notice the changes. Although we may not see the changes, the physical and chemical properties of rocks are constantly changing in a natural, never-ending cycle called the rock cycle.

Differences in temperature, pressure, and structural formations in the mantle and crust cause magma to form in different ways. The rifting movement causes the buoyant magma below to rise and fill the space of lower pressure. The rock then cools into new crust.

It melts. The same thing happens to a rock when it is heated enough. Of course, it takes a lot of heat to melt a rock. It takes temperatures between 600 and 1,300 degrees Celsius (1,100 and 2,400 degrees Fahrenheit) to melt a rock, turning it into a substance called magma (molten rock).

It melts at 2072 C or 3762 F. Stone buildings are never immune to fire though. Old ones were often built with wooden supports and extreme temperature gradients cause rocks to crack before they melt. It is better to be impossible to light on fire in the first place than it is to try to resist a fire.

Four basic processes are involved in the formation of a clastic sedimentary rock: weathering (erosion)caused mainly by friction of waves, transportation where the sediment is carried along by a current, deposition and compaction where the sediment is squashed together to form a rock of this kind.

Most minerals can be characterized and classified by their unique physical properties: hardness, luster, color, streak, specific gravity, cleavage, fracture, and tenacity.

Three Types of Rock: Igneous, Sedimentary & Metamorphic | AMNH.

zircons

A conservative estimate is that each of these steps would take approximately 20 million years (some may be less, others would be more, and some could be much more).

The formation of clastic and organic rocks begins with the weathering, or breaking down, of the exposed rock into small fragments. Through the process of erosion, these fragments are removed from their source and transported by wind, water, ice, or biological activity to a new location.

The rock cycle begins with molten rock (magma below ground, lava above ground), which cools and hardens to form igneous rock. Exposure to weathering and erosional forces, break the original rock into smaller pieces.

The rock cycle is a process in which rocks are continuously transformed between the three rock types igneous, sedimentary and metamorphic. Sediments are produced when rocks are uplifted, weathered and eroded, and the resulting detrital material deposited in marine or terrestrial basins.

The rock cycle is predictable and provides insight into the probable locations of energy sources. For example, fossil fuels are found in sedimentary environments while radioactive elements for nuclear energy (uranium) may be found in igneous or sedimentary environments.

The process of transformation of rocks from one form to an other in a cyclic manner is known as the rock cycle. Hot lava cools down to form igneous rocks. These igneous rocks are then broken down into small particles which are transported and then deposited. This results in the formation of sedimentary rocks.

Inside Earth, heat, pressure, and melting change sedimentary and igneous rock into metamorphic rock. Intense heating results in hot liquid rock (magma) bursting through Earth’s surface and turning into solid igneous rock. Over time, this rock gets weathered and eroded, and the cycle begins again.

Types of minerals

• Native elements. eg. Gold, Silver, Mercury, graphite, diamond.
• Oxides. eg corundum (incl. sapphire), hematite, spinel.
• Hydroxides. eg. Goethite, brucite.
• Sulfides. eg. Pyrite, galena, sphalerite.
• Sulfates. eg. Baryte, gypsum.
• Carbonates. eg. Calcite, magnesite, dolomite.
• Phosphates. eg.
• Halides. eg.

Rocks can grow taller and larger Rocks also grow bigger, heavier and stronger, but it takes a rock thousands or even millions of years to change. Water also contains dissolved metals, which can “precipitate” out of seawater or freshwater to grow rocks. These rocks are called concretions or nodules.